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Definition of brainless

brainless

/ˈbreɪn.ləs/
brain · less
Adverb:brainlessly
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brainless Lexical Profile

brainless Game Scores & Validity

• adjective

1

Lacking intelligence, common sense, or sound judgment; foolish or stupid.

Example

"Leaving the car unlocked in a busy parking lot was a rather brainless mistake."

2

Anatomically lacking a brain, as certain simple invertebrates.

Example

"Jellyfish and sea stars are brainless organisms that rely on decentralized nerve nets to respond to their environment."

Synonyms
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Antonyms
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• Rhymes for brainless

• Nearby Words

brainfood
brainiac
braininess
brainless
brainlessly
brainlessness
brainpower

Word Origin & Etymology

Formed in Middle English from the noun 'brain' (from Old English 'brægen') and the privative suffix '-less'.

Cite this Entry

Wordmom. (2026). Definition of Brainless. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/brainless
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