brainy

As an adjective brainy

is (informal) very intellectually capable.

As a noun geek is

(dated) a carnival performer specializing in bizarre and unappetizing behavior or geek can be (australia|colloquial) a look.

As a verb geek is

(colloquial) to get high on cocaine.

As a noun nerd

is nerd (a person, often very studious, with poor social skills).

As an adjective brainy is

(informal) very intellectually capable.

As adjectives the difference between erudite and brainy

is that erudite is while brainy is (informal) very intellectually capable.

As adjectives the difference between brainy and undefined

is that brainy is (informal) very intellectually capable while undefined is lacking a definition or value.

As adjectives the difference between witless and brainy

is that witless is destitute of wit or understanding; wanting thought; hence, indiscreet; not under the guidance of judgment while brainy is (informal) very intellectually capable.

As a noun smarty

is an obnoxiously clever or quick-witted person; a smart aleck.

As an adjective brainy is

(informal) very intellectually capable.

As adjectives the difference between brainy and stupid

is that brainy is (informal) very intellectually capable while stupid is lacking in intelligence or exhibiting the quality of having been done by someone lacking in intelligence.

As an adverb stupid is

(slang|dated) extremely.

As a noun stupid is

a stupid person; a fool.

As adjectives the difference between knowledgeable and brainy

is that knowledgeable is having knowledge, especially of a particular subject while brainy is (informal) very intellectually capable.

As adjectives the difference between inteligent and brainy

is that inteligent is intelligent while brainy is (informal) very intellectually capable.

Bookish is a related term of brainy.

As adjectives the difference between bookish and brainy

is that bookish is given to reading; fond of study; better acquainted with books than with people; learned from books while brainy is (informal) very intellectually capable.