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Definitions

invertebrate

[in-vur-tuh-brit, -breyt] / ɪnˈvɜr tə brɪt, -ˌbreɪt /
ADJECTIVE
ineffective/ineffectual
Synonyms
WEAK
abortive anticlimactic barren bootless defeasible feckless feeble forceless fruitless futile idle impotent inadequate incompetent indecisive inefficacious inefficient inept inferior innocuous inoperative lame limited neutralized nugatory null null and void paltry powerless spineless unable unavailing unfruitful unproductive unprofitable unsuccessful vain void withered worthless
Antonyms
WEAK
competent effective effectual efficient powerful strong useful
ADJECTIVE
inefficacious
Synonyms
WEAK
abortive anticlimactic barren bootless defeasible feckless feeble forceless fruitless futile idle impotent inadequate incompetent indecisive ineffective inefficient inept inferior innocuous inoperative lame limited neutralized nugatory null null and void paltry powerless spineless unable unavailing unfruitful unproductive unprofitable unsuccessful useless vain void withered worthless
ADJECTIVE
spineless
Synonyms
WEAK
amoebalike faint-hearted fearful feeble forceless frightened gutless impotent inadequate ineffective ineffectual irresolute lily-livered nerveless pithless soft spiritless squeamish submissive timid vacillating weak weak-kneed weak-willed yellow yellow-bellied
Antonyms
WEAK
bold brave strong
NOUN
animal
Synonyms
STRONGEST
beast creature pet
STRONG
being brute critter mutt stray varmint vertebrate
WEAK
living thing wild thing
Antonyms
WEAK
mineral plant
NOUN
coward
Synonyms
STRONGEST
wimp
STRONG
alarmist baby chicken craven cur dastard deserter jellyfish malingerer mouse pessimist poltroon quitter rabbit recreant shirker skulker sneak weakling
WEAK
chickenheart faint-of-heart faintheart fraidy-cat gutless wonder lily liver scaredy-cat shirk white liver yellowbelly
Antonyms
WEAK
aggressor hero
NOUN
weakling
Synonyms
STRONGEST
wimp
STRONG
baby chicken coward crybaby jellyfish misfit pushover
WEAK
chickenheart cream puff dotard yellowbelly
Antonyms
WEAK
strongman
NOUN
weak sister
Synonyms
WEAK
chicken gutless wonder hothouse plant jellyfish meek soul softy weak soul weakling

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Scientists have long wondered how these invertebrate eyes continue growing during adulthood.

From Science Daily • Dec. 2, 2025

Typically, a spooked tarantula will try to run and hide, said Lisa Gonzalez, program manager of invertebrate living collections at the county Natural History Museum.

From Los Angeles Times • Oct. 25, 2025

After a fire in the area in April 2021, the National Trust conducted a survey for invertebrates and found "a 90% reduction in invertebrate life" from burnt land compared to areas that remained unburnt.

From BBC • Apr. 11, 2025

Besides serving as a national cultural symbol, turkeys play an important role in the environment, dispersing seeds and helping to control invertebrate populations.

From Salon • Nov. 28, 2024

The invertebrate eye was invented into an optical instrument at the MBL, opening the way to modern visual physiology.

From "The Lives of a Cell" by Lewis Thomas

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