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Definition of brainbox
brainbox
/ˈbreɪn.bɑːks/
brain · box
Plural:brainboxes
brainbox Lexical Profile
CEFR
B2
Grade
6
Tier
3
Usage
Rare
brainbox Game Scores & Validity
Scrabble US
Scrabble UK
WWF
Wordle Guess
• noun
1
British A very intelligent or academically gifted person.
Example
"My sister was always the brainbox of the family, effortlessly passing her exams while I struggled."
2
The human skull or cranium, specifically the protective bony portion enclosing the brain.
Example
"The boxer took a heavy, disorienting blow to the brainbox and stumbled toward the ropes."
Synonyms
View all synonyms for brainbox Antonyms
View all antonyms for brainboxWord Nuance & Usage
Primarily used in British English as an informal, sometimes affectionate or slightly teasing term for someone who is exceptionally smart.
• Nearby Words
Word Origin & Etymology
A compound of 'brain' and 'box'. Originally coined in the 19th century as a slang term for the skull, its meaning shifted by the early 20th century to denote a highly intelligent person.
Cite this Entry
Wordmom. (2026). Definition of Brainbox. In Wordmom Dictionary. Retrieved Oct 18, 2026, from https://wordmom.com/dictionary/brainbox