Brainy

adj.capableplayful

What it means

Noticeably intelligent and quick with demanding ideas.

Reach for it when giving informal or playful praise for intellectual ability

The brainy contestant spotted the hidden assumption before anyone reached for a calculator.

everyday
brilliant
when ability is truly exceptional rather than simply strong
not when Calling every capable person brilliant weakens the praise and overstates the evidence.
everyday
clever
when quick understanding or an inventive solution stands out
not when Clever may praise one trick without claiming deep intellectual strength.
everyday
sharp
when alert perception and fast judgment are central
not when Sharp says little about accumulated knowledge or scholarly interests.
everyday
smart
when direct, familiar praise fits the audience
not when Smart can also mean stylish, so the sentence may need more context.
warm
bright
when intelligence is paired with promise, especially in a young person
not when Bright is gentler and does not carry brainy's enthusiastically academic flavor.
warm
quick-witted
when fast verbal or mental responses deserve attention
not when A slow, profound thinker can be brainy without being quick-witted.
professional
intelligent
when a neutral, respectful judgment of mental ability is needed
not when Intelligent is broader and less playful than brainy.
formal
cerebral
when a person or work appeals primarily to intellect
not when Cerebral can imply emotional distance and is not a simple compliment for intelligence.

brainy student
The brainy student built a proof from clues others had dismissed.
brainy idea
A brainy idea turned the storage problem into a simple labeling rule.
brainy humor
The play's brainy humor rewards anyone who enjoys linguistic puzzles.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.