thought
understanding
reflection
reason
an idea, a notion
an inkling
curious
thoughtful
unthinkable
to conceive
to understand, to graps
to perceive, to make out
to observe
to notice
to concentrate on, to focus on
to contemplate
to consider
to ponder over, to meditate on
to look into something
to reflect (up) on something
to realize
knowledge
know-how
learning
education
general knowledge
literacy
illiteracy
meaning
ignorance
an intellectual
educated // uneducated
cultivated, cultured
learned, erudite
illiterate
ignorant
self-taught
unknown
to know
to mean
reasoning
logic
a theory
a hypothesis
a supposition, a assumption, a presumption
inference, deduction
analysis
an explanation
a solution
a conclusion, an outcome
a fact
proof, evidence
rational // irrational
logical // illogical
consistent // inconsistent
groundless
accurate
theoretical
to baffle, to puzzle
to look for, to search, to seek
to deduce, to infer
to suppose, to assume, to presume
to speculate on, about
to interpret
to suspect
to prove
to find
to discover, to find out
to solve
to explain
to demonstrate, to establish
to confirm
to reveal, to disclose
to expose
choice
a comparison
a decision
a contrast
a dilemma
a preference
choosy, picky
favo(u)rite
undecided
compared to
comparatively
preferably
to decide
to compare
to oppose, to contrast
to choose
to pick out
what do you think
what are you thinking of
she always thinks big
on second thoughts
let me think
to formulate a hypothesis
to bear out / to confirm a hypothesis
it has just dawned on me that
it stands to reason
draw your own conclusions
it's up to you
to make a decision
to make up one's mind
to change one's mind
do as you choose
to think about
to think something over
to think up
to think back
to think ahead
to think something out
i would rather / i'd rather
i prefer