- aberrant
- aberrated
- aberrational
- able
- abnormal
- above your head
- abreast
- abreast of
- abreast of the facts
- abstract
- abstruse
- absurd
- academic
- accomplished
- accustomed
- acquainted
- acquainted with
- acroamatic
- across
- acute
- advanced
- advised
- aesthetic
- airy
- alert
- alien
- alive
- all Greek to me
- all Greek to someone
- all Greek to you
- all there
- all your own
- all-knowing
- all-seeing
- all-wise
- allowed
- almighty
- altered
- alternate
- alternative
- amazing
- ambagious
- ambiguous
- ambivalent
- amphibological
- amusing
- anagogic
- analytic
- analytical
- anarchic
- anomalistic
- anomalous
- anticonventional
- antiestablishment
- antitraditional
- aperiodic
- apocryphal
- appreciative
- apprehensive
- apprised
- apprised of
- apprized
- apt
- arbitrary
- arcane
- arduous
- arguable
- argute
- art-house
- artful
- artistic
- artistically aware
- arty
- arty-farty
- as clear as mud
- asinine
- astonishing
- astute
- at ease with
- at home
- at home with
- atypic
- atypical
- au courant
- au courant with
- au fait
- au fait with
- avant garde
- avant-garde
- aware
- aware of
- awe-inspiring
- awesome
- awkward
- back-alley
- back-door
- backdoor
- backhanded
- backroom
- backstage
- backstair
- backstairs
- baffling
- balanced
- balmy
- bamboozling
- barbarous
- barmy
- baroque
- basic
- batty
- beat
- beatnik
- beats me
- behind someone’s back
- behind the scenes
- behind-the-scenes
- bemusing
- bent
- between ourselves
- between the lines
- between you and me
- between you and me and the bedpost
- between you and me and the doorpost
- between you and me and the gatepost
- between you and me and the wall
- bewildering
- beyond comprehension
- beyond one
- beyond one’s grasp
- beyond understanding
- beyond you
- beyond your ken
- bizarre
- bizarro
- black
- blue
- blue-sky
- blue-stocking
- bluestocking
- blurred
- blurry
- bohemian
- Bohemian
- boho
- bold
- bonkers
- book-loving
- bookish
- bookworm
- borderline
- bosom
- bottled up
- brain
- brainless
- brainy
- breaking new ground
- briefed
- bright
- brilliant
- broad-minded
- bubbleheaded
- bugged out
- buried
- buttoned up
- byzantine
- Byzantine
- cabalistic
- cabbalistic
- cached
- cagey
- calculating
- camouflaged
- camp
- campy
- can of worms
- canny
- capable
- capable of learning
- capricious
- careful
- carefully guarded
- carny
- casual
- casuistic
- casuistical
- catlike
- catty
- cautious
- censored
- cerebral
- challenging
- chance
- chancy
- characteristic
- chivalrous
- circuitous
- circular
- circumlocutionary
- circumlocutory
- circumspect
- civilised
- civilized
- clandestine
- classic
- classified
- clear as dishwater
- clear as mud
- clear-eyed
- clear-sighted
- clerkly
- clever
- cloak and dagger
- cloak-and-dagger
- cloaked
- close
- close to one’s chest
- closed
- closely guarded
- closet
- clouded
- cloudy
- clownish
- clued in
- clued in on
- clued up
- clued up about
- clued up on
- clued-up
- cluey
- coached
- cock-eyed
- cockamamie
- cockeyed
- coded
- cogitative
- cognitive
- cognizant
- cognizant in
- cognizant of
- coherent
- comic
- comical
- commonsense
- commonsensible
- commonsensical
- competent
- competent at
- complex
- complicate
- complicated
- comprehending
- concealed
- conceptual
- confident
- confident with
- confidential
- confounding
- confused
- confusing
- congruent
- conjectural
- conjectured
- conscious
- consequent
- conspicuous
- conspiratorial
- contemplative
- contemporary
- contentious
- contingent
- contradictory
- contrarian
- contrary
- controlled
- controversial
- controvertible
- conversant
- conversant with
- convoluted
- cool
- corrected
- corrupt
- cosmopolitan
- counterintuitive
- courteous
- couth
- covered
- covered up
- covert
- cowardly
- cracked
- crackers
- crackpot
- crafty
- cranky
- crazy
- creative
- creepy
- cryptic
- cryptical
- cuckoo
- cultivated
- cultured
- cumbersome
- cunning
- curious
- current
- daedal
- Daedalean
- Daedalian
- daffy
- daft
- daggy
- dainty
- dark
- darkest
- debatable
- deceitful
- deceptive
- decontrolled
- deep
- deep-seated
- deepest
- deliberated
- delicate
- Delphian
- Delphic
- demented
- dense
- dern
- designing
- desirable
- detailed
- developed
- deviant
- deviate
- deviating
- devious
- diagnostic
- diagnostical
- different
- difficult
- difficult to understand
- dilly
- dippy
- dirty
- discerning
- disconcerting
- disconsonant
- discontinuous
- discordant
- discreet
- discriminating
- disguised
- disorderly
- disparate
- disputable
- disputed
- disquieting
- disreputable
- dissembled
- dissembling
- dissimilar
- dissimulated
- distinct
- distinctive
- distingue
- distinguished
- distinguishing
- distorted
- divergent
- dodgy
- donnish
- dotty
- double Dutch
- double-edged
- doubtable
- doubtful
- down
- down with
- down-to-earth
- drawn-out
- droll
- dubious
- dubitable
- dumb
- duplicitous
- dynamite
- earnest
- eccentric
- eccentrical
- educated
- eerie
- egghead
- eggheaded
- egregious
- elaborate
- elegant
- elliptic
- elliptical
- elusive
- elusory
- eminent
- enciphered
- encoded
- enigmatic
- enigmatical
- enlightened
- enlightened about
- enriched
- enshrouded
- entangled
- episodic
- episodical
- equivocal
- equivocating
- errant
- erratic
- erudite
- esophagogastroduodenoscopies
- esophagogastroduodenoscopy
- esophagus
- esophoria
- esophorias
- Esopic
- esoteric numeration
- esoterically
- esotericism
- esotericisms
- esotericist
- esotericists
- especial
- essential
- esthetic
- evasive
- exact
- exceeding
- excentric
- excentrical
- exceptional
- exciting
- exclusive
- exotic
- experienced
- experienced in
- experimental
- expert
- exquisite
- extraordinaire
- extraordinary
- extravagant
- extreme
- extremist
- eye-popping
- eyes-only
- faint
- false
- familiar
- familiar with
- familiarised
- familiarized
- fanciful
- fancy
- fantastic
- fantastical
- far out
- far-fetched
- far-out
- farcical
- farsighted
- fast
- fathomless
- fatuous
- featherheaded
- feline
- few
- few and far between
- fiddly
- filled in
- fine
- fine-drawn
- fine-spun
- finespun
- finished
- firm
- fishy
- fitted
- flakey
- flaky
- flimsy
- fluky
- fly
- foggy
- fool
- foolhardy
- foolish
- for eyes only
- foreign
- foreign-looking
- foresighted
- formed
- formidable
- foxy
- fraudulent
- freak
- freakish
- freaky
- free
- free-spirited
- freethinking
- freewheeling
- fresh
- fringe
- fruity
- fuliginous
- full of common sense
- full of insight
- full of surprises
- full of twists and turns
- fundamental
- funky
- funny
- funny peculiar
- funny strange
- furtive
- fuzzy
- gallant
- garbled
- geared up
- geeky
- general
- genius
- genned up
- genned up about
- genned up on
- genteel
- gifted
- glamorous
- glamourous
- gnarly
- gnomic
- gonzo
- good
- goofy
- Gordian
- gracious
- granted
- grave
- gray
- great
- Greek
- Greek to me
- grey
- groovy
- grotesque
- groundbreaking
- grounded
- guarded
- guileful
- hair-splitting
- hairline
- hairsplitting
- half-baked
- half-cracked
- half-witted
- hard
- hard to explain
- hard to follow
- hard to solve
- hard to understand
- hare-brained
- harebrained
- having a good head on one’s shoulders
- having all one’s marbles
- having been around
- having no flies on
- having your finger on the pulse
- hazy
- headstrong
- heavy
- hep
- hep to
- heretic
- heretical
- hermetic
- hermetical
- heteroclite
- heterodox
- heterogeneous
- heteromorphic
- hi-tech
- hidden
- hidden away
- hidden from sight
- hidden from view
- high-class
- high-flown
- high-tech
- highbrow
- highbrowed
- higher
- hip
- hip to
- hippie
- hippy
- hole and corner
- hole-and-corner
- hole-in-the-corner
- holed up
- hot
- hugger-mugger
- humorous
- hush-hush
- hushed
- hushed up
- hyperintelligent
- hypothetical
- ideal
- ideational
- identifying
- ideological
- idiosyncratic
- idiotic
- iffy
- ill-conceived
- ill-defined
- illegal
- illegible
- illegitimate
- illicit
- illogical
- illuminated
- imaginative
- immaterial
- impalpable
- impenetrable
- implicit
- implied
- impossible to understand
- impracticable
- impractical
- imprecise
- impressionistic
- impressive
- imprudent
- in
- in ambush
- in camera
- in confidence
- in control
- in dispute
- in doubt
- in holes and corners
- in left field
- in on
- in one’s right mind
- in private
- in question
- in secret
- in strict confidence
- in the circle
- in the know
- in the know about
- in the loop
- in the picture
- in touch
- inaccessible
- inane
- inapropos
- inarticulate
- inaudible
- incalculable
- incog
- incognito
- incognizable
- incoherent
- incomparable
- incomprehensible
- inconceivable
- inconclusive
- incongruent
- incongruous
- inconspicuous
- incorporeal
- incredible
- indecipherable
- indecisive
- indefinite
- independent
- indescribable
- indeterminate
- indigestible
- indirect
- indiscernible
- indistinct
- indistinguishable
- individual
- individualistic
- inept
- inexact
- inexplainable
- inexplicable
- inexplicit
- inextricable
- infantile
- infinite
- informal
- informed
- informed about
- infrequent
- ingenious
- inimitable
- initiated
- inmost
- inner
- innermost
- innovative
- innovatory
- insane
- inscrutable
- inside
- insidious
- insightful
- insoluble
- insolvable
- instructed
- insubstantial
- intangible
- intellective
- intellectual
- intellectualist
- intellectualistic
- intellectually aware
- intelligence
- intelligent
- intense
- interesting
- interlaced
- intermittent
- internal
- intimate
- intimately aware
- into
- intrapersonal
- intricate
- intriguing
- introduced
- intuitive
- inventive
- invisible
- involute
- involuted
- involved
- inward
- irrational
- irregular
- irrelevant
- irresolvable
- isolated
- issuable
- ivory-tower
- ivory-towered
- ivory-towerish
- jerky
- jesuitic
- joshing
- judicious
- jumbled
- just
- justified
- keen
- kept concealed
- kept posted
- kept secret
- kinky
- knotted
- knotty
- know how many beans make five
- know one’s stuff
- knowing
- knowing the score
- knowing what’s what
- knowledgeable
- knowledgeable about
- kookie
- kookish
- kooky
- labored
- laboured
- labyrinthian
- labyrinthic
- labyrinthine
- laughable
- learned
- leet
- left-field
- lettered
- level-headed
- levelheaded
- liberal
- liberated
- light-hearted
- like nothing on earth
- limited
- literary
- literate
- little known
- little-known
- logical
- long-drawn-out
- long-haired
- longhair
- looney
- loony
- loopy
- lost to view
- low-down
- low-key
- ludicrous
- lunatic
- lunkheaded
- mad
- madcap
- magical
- malformed
- mannerly
- marginal
- marked
- marvellous
- marvelous
- masked
- matter-of-fact
- mature
- maverick
- maze-like
- mazelike
- mazy
- meaningless
- memorable
- mental
- metaphysical
- mind-bending
- mind-blowing
- mind-boggling
- mindful
- mindly
- minuscule
- minute
- misleading
- mixed
- mixed up
- modern
- modernistic
- modified
- mom
- monstrous
- moot
- muddled
- muddy
- multifaceted
- multifarious
- multivocal
- mum
- mumbled
- murky
- muzzy
- mysterial
- mysterious
- mystic
- mystical
- mystifying
- nameless
- narrow
- nebulous
- need to know
- negotiable
- nerdish
- nerdy
- new
- nice
- nimble
- no stranger to
- no-nonsense
- noiseless
- non-committal
- non-practical
- non-public
- non-standard
- non-technical
- non-typical
- noncommittal
- nonconcrete
- nonconforming
- nonconformist
- nonconservative
- nonconventional
- nondescript
- nonfigurative
- nonintuitive
- nonmainstream
- nonorthodox
- nonpublic
- nonrepresentational
- nonsensical
- nonstandard
- nontraditional
- not definite
- not easily understood
- not for circulation
- not for public consumption
- not for publication
- not in the public domain
- not normal
- not obvious
- not open
- not public
- not tightly wrapped
- not to be disclosed
- not to be made public
- not to be mentioned
- not to be quoted
- not visible
- notable
- noteworthy
- notional
- novel
- nuanced
- numinous
- nurtured
- nuts
- nutty
- obfuscated
- oblique
- obliquitous
- obscure
- obscured
- observant
- occasional
- occult
- odd
- oddball
- off Broadway
- off the air
- off the beaten path
- off the beaten track
- off the rails
- off the record
- off the wall
- off-base
- off-beat
- off-center
- off-centre
- off-color
- off-colour
- off-key
- off-kilter
- off-the-record
- off-the-wall
- offbeat
- offhand
- offstage
- omniscient
- on the ball
- on the beam
- on the QT
- on the quiet
- on the sly
- on to
- on top of things
- one and only
- one of a kind
- one-off
- one-on-one
- ontological
- opaque
- open
- open to argument
- open to debate
- open to discussion
- open to doubt
- open to question
- open-minded
- oracular
- original
- ornate
- orphic
- other
- out in left field
- out of keeping
- out of line
- out of place
- out of sight
- out of the common
- out of the ordinary
- out of the way
- out of this world
- out of view
- out there
- out-of-the-way
- out-there
- outlandish
- outrageous
- outre
- outré
- outside
- outstanding
- over one’s head
- overnice
- oversubtle
- pacesetting
- pansophic
- pansophical
- paradigmatic
- paradoxical
- part of the circle
- particular
- peculiar
- pedagogical
- pedantic
- penetrating
- perceptive
- perceptual
- percipient
- perdu
- perfect in
- periodic
- periodical
- peripheral
- periphrastic
- perplexing
- personal
- perspicacious
- perverse
- perverted
- petty
- phenomenal
- philosophic
- philosophical
- phrenic
- pioneering
- planted
- plugged in
- plugged in to
- plugged into
- plugged-in
- pointless
- polished
- polite
- politic
- polymath
- polysemantic
- polysemic
- polysemous
- posted
- postmodern
- postmodernist
- potty
- practical
- practiced
- practised
- practised in
- pragmatic
- precise
- precocious
- preeminent
- prepared
- preposterous
- prescient
- preternatural
- prevaricating
- primed
- private
- privileged
- privy
- problematic
- problematical
- prodigious
- professional
- professorial
- proficient
- proficient in
- profound
- progressive
- progressivist
- prominent
- protected
- prudent
- psychical
- psychological
- puerile
- pure
- put in the hole
- putative
- puzzling
- quaint
- qualified
- queer
- queerish
- questionable
- quick
- quick on the uptake
- quick-witted
- quiet
- quirky
- quizzical
- rad
- radical
- raffish
- rambling
- ramified
- random
- rare
- rarefied
- ratiocinative
- rational
- raveled
- ravelled
- ready
- realistic
- really hard
- reasonable
- reasoned
- reasoning
- recherche
- recherché
- recondite
- refined
- reflective
- reforming
- reformist
- refreshing
- regulated
- reliable
- remarkable
- remote
- representative
- repressed
- reserved
- resourceful
- responsible
- restricted
- restricted access
- revisionist
- revolutionary
- riddling
- ridiculous
- risible
- rococo
- romantic
- roundabout
- rum
- rummy
- sagacious
- sage
- sane
- sapient
- sappy
- savant
- savvy
- scarce
- scattered
- scheming
- schismatic
- schizoid
- scholarly
- scholastic
- schooled
- scientific
- scrambled
- screened
- screwball
- screwy
- sealed
- seasoned
- secondary
- secret
- secreted
- secretive
- sectarian
- seldom
- seldom seen
- self-referential
- semioccasional
- sensational
- senseless
- sensible
- sensitive
- sentient
- serious
- serious-minded
- serpentine
- shadowy
- shady
- shaky
- shaped
- sharp
- sharp-witted
- shifty
- shonky
- showing great knowledge
- shrewd
- shrouded
- shrouded in mystery
- shuffling
- sibylline
- signal
- significant
- silent
- silly
- simpleminded
- singular
- sinuous
- sketchy
- skilled
- skilled in
- skittish
- skulking
- slick
- slim
- slinking
- slippery
- slurred
- sly
- smart
- sneak
- sneaking
- sneaky
- snide
- sober
- soft
- solemn
- solid
- something else
- sophistical
- sophisticated
- sound
- spaced-out
- sparse
- spasmodic
- special
- specialised
- specialist
- specialized
- specific
- speculative
- sphinxlike
- spooky
- sporadic
- spurious
- spy
- standout
- startling
- stashed
- steady-going
- stealth
- stealthy
- stellar
- stickling
- stonewalling
- strange
- strategic
- street-smart
- streetwise
- strict
- strictly confidential
- striking
- studied
- studious
- stumping
- stupid
- sub rosa
- sub-rosa
- subconscious
- subjective
- subliminal
- subtle
- superior
- supernatural
- supersmart
- suppositional
- suppositious
- suppositive
- suppressed
- sure
- surprise
- surprising
- surreal
- surreptitious
- suspect
- suspicious
- sussed
- switched on
- switched on to
- switched-on
- swotty
- symptomatic
- tactful
- tactical
- talented
- tangled
- tasteful
- taught
- taxing
- teasing
- technical
- tenebrous
- tentative
- tenuous
- tête-à-tête
- theoretic
- theoretical
- thin on the ground
- thinking
- thorny
- thought-provoking
- thoughtful
- tight
- tight-lipped
- tiny
- to be kept under wraps
- together
- tolerant
- tomfool
- too deep
- too difficult to understand
- too hard to understand
- top-notch
- top-secret
- top-shelf
- tortuous
- touched
- tough
- trained
- transcendent
- transcendental
- traveled
- travelled
- trendsetting
- tricky
- trifling
- troublesome
- tucked away
- tuned in
- tuned-in
- turned on
- tutored
- twisted
- two-edged
- typical
- ulterior
- ultra-fine
- ultramodern
- ultrasmart
- unable to be solved
- unaccountable
- unaccustomed
- unacknowledged
- unanswerable
- unapparent
- unauthenticated
- unauthorised
- unauthorized
- unbalanced
- unbowed
- uncanny
- unceremonious
- uncertain
- uncertified
- uncharacteristic
- unclear
- unco
- uncommon
- uncommunicated
- uncomprehensible
- unconfirmed
- unconforming
- unconstrained
- uncontrolled
- unconventional
- uncorroborated
- uncustomary
- undecided
- undecipherable
- undeclared
- undefinable
- undefined
- under advisement
- under cover
- under examination
- under one’s hat
- under the table
- under wraps
- under-the-counter
- under-the-table
- undercover
- underground
- underhand
- underhanded
- underlying
- understanding
- undetermined
- undisciplined
- undisclosed
- undivulged
- undocumented
- unendorsed
- unenlightened
- unexpected
- unexplainable
- unexplained
- unexplicit
- unexplored
- unexpressed
- unfamiliar
- unfathomable
- unfettered
- unfrequent
- ungraspable
- unhampered
- unharmonious
- unhealthy
- unheard of
- unheard-of
- unhinged
- unidentified
- unimaginable
- unintelligible
- uninterpretable
- unintuitive
- uninvestigated
- unique
- unknowable
- unknown
- unlikely
- unmentioned
- unnamed
- unnarrated
- unnatural
- unnormal
- unnoticeable
- unobtrusive
- unofficial
- unordinary
- unorthodox
- unparalleled
- unpractical
- unpragmatic
- unprecedented
- unpredictable
- unprofessed
- unprovable
- unproved
- unproven
- unprovincial
- unpublished
- unratified
- unreadable
- unreal
- unrealistic
- unreasonable
- unrecognised
- unrecognized
- unrecounted
- unregimented
- unrelatable
- unreliable
- unreported
- unrepresentative
- unresolvable
- unresolved
- unrestrained
- unrevealed
- unsaid
- unsanctioned
- unseen
- unsettled
- unsolvable
- unsolved
- unspecific
- unspoken
- unstated
- unsubstantiated
- unsure
- unthinkable
- untold
- untraditional
- untrammeled
- untrammelled
- untried
- untypical
- unusual
- unverified
- unvoiced
- unwieldy
- unwise
- unwonted
- unworkable
- up
- up on
- up to date
- up to date on
- up to speed
- up to speed on
- up with
- up-to-date
- up-to-the-minute
- urbane
- used to
- useless
- vacillating
- vague
- valid
- variant
- variegated
- veiled
- versant
- versed
- versed in
- very different
- very hard
- very smart
- very unconventional
- very unique
- very unusual
- vexing
- wacko
- wacky
- warped
- way out
- way-out
- wayward
- weak-minded
- weighty
- weird
- weird and wonderful
- weirdo
- well advised
- well briefed
- well educated
- well informed
- well informed about
- well judged
- well mannered
- well read
- well reasoned
- well thought out
- well up
- well up in
- well up on
- well versed
- well versed in
- well-acquainted
- well-advised
- well-bred
- well-briefed
- well-educated
- well-founded
- well-grounded
- well-informed
- well-read
- well-reasoned
- well-rounded
- well-taught
- well-thought-out
- well-versed
- whacky
- whimsical
- whip-smart
- whiz
- widely read
- wigged out
- wild
- wildering
- wilful
- willful
- wily
- winding
- wise
- wise to
- wise up
- with a knowledge of
- with a lid on
- with an understanding of
- with good taste
- with great knowledge
- with it
- with-it
- within these four walls
- without a solution
- witless
- witting
- witty
- wonderful
- worldly
- worldly-wise
- worrying
- yellow
- zany