acute
apperceptive
apprehensive
discerning
discriminating
incisive
insightful
keen
knifelike
observant
observing
penetrating
penetrative
piercing
quick-sighted
sharp
sharp-eyed
sharp-sighted
subtle
understanding
alert
alive
alive to
all-knowing
appercipient
apprehending
argute
astute
attentive
aware
cogent
cognizant
comprehending
conscious
farseeing
farsighted
foreseeing
foresighted
forethoughted
forethoughtful
gnostic
impressible
impressionable
impressive
intelligent
intuitional
intuitive
judicious
knowing
knowledgeable
longheaded
longsighted
mindful
omniscient
on the ball
percipient
perspicacious
perspicuous
prehensile
perceive
perception
perceptively
perceptivity
analytic
appreciative
discern
inventive
lucid
penetrate
persuasive
receptive
reflective
resourceful
self-possessed
shrewd
sympathetic
talented
well-informed
contraceptive
deceptive
unreceptive