The quality of being brainy; intelligence, cleverness, or mental ability.
Noun form derived from 'brainy' by adding the -ness suffix (Old English origin), which converts adjectives into abstract nouns representing their qualities.
The word 'braininess' treats intelligence as a measurable quality or substance, which is interesting scientifically—IQ tests claim to measure it, but neuroscientists know intelligence is incredibly complex with no single 'brain power' measure.
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