2
feather-brained
2
flaky(foolish, unreasonable, illogical)
2
flighty(adjective, simple, careless, foolish, stupid)
2
futile(dull, unintelligent, witless)
2
gormless
2
halfwitted
2
hare-brained
2
indiscreet(adjective, dull, weak, simple, silly)
2
jackass(noun, adjective, foolish)
2
kooky(weak, simple, silly, foolish, unreasonable)
2
laughable(adjective, dull, unintelligent, witless)
2
lumpish
2
nitwit(noun, adjective, foolish)
2
nitwitted(adjective, simple, silly, foolish, stupid)
2
not bright(expression, adjective, simple, slow, stupid)
2
pea-brained
2
pointless(dull, silly, foolish, stupid, absurd)
2
preposterous(adjective, weak, simple, silly, foolish)
2
rash(adjective, dull, silly, thoughtless, unwise)
2
rattle-brained
10 years ago|15k views|share |citing 
APASmart Define. (2016). brainless thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/brainless/thesaurus/synonyms
ChicagoSmart Define. 2016. "brainless thesaurus" https://smartdefine.org/brainless/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, brainless thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/brainless/thesaurus/synonyms>.
MLASmart Define. "brainless thesaurus" 24 March 2016. Web. 20 September 2026. <https://smartdefine.org/brainless/thesaurus/synonyms>