agile
apt
born
brainy
bright
brilliant
clever
innate
natural
nimble
prehensile
quick
rational
ready
reasonable
scintillating
searching
sensible
smart
smart as a whip
sophisticated
trenchant
acute
adroit
alert
all-knowing
apperceptive
appercipient
apprehending
apprehensive
astute
au fait
aware
canny
cerebral
cognizant
communicative
comprehending
conceptive
conceptual
conscious
consequent
cunning
discerning
discursive
docile
educable
endopsychic
enlightened
erudite
facile
formable
gifted
ideational
impressionable
ingenious
insightful
instructable
intellectual
internal
keen
knowing
knowledgeable
logical
active
honest
sensitive
shrewd
thoughtful
stupid