invertebrate

American  

[in-vur-tuh-brit, -breyt] / ɪnˈvɜr tə brɪt, -ˌbreɪt /

adjective

1. Zoology.

   1. not vertebrate; without a backbone.

   2. of or relating to creatures without a backbone.

2. without strength of character.

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noun

1. an invertebrate animal.

2. a person who lacks strength of character.

invertebrate British  

/ -ˌbreɪt, ɪnˈvɜːtɪbrɪt /

noun

1. any animal lacking a backbone, including all species not classified as vertebrates

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adjective

1. of, relating to, or designating invertebrates

invertebrate Scientific  

/ ĭn-vûr′tə-brĭt,-brāt′ /

1. Having no backbone or spinal column.

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1. An animal that has no backbone or spinal column and therefore does not belong to the subphylum Vertebrata of the phylum Chordata. Most animals are invertebrates. Corals, insects, worms, jellyfish, starfish, and snails are invertebrates.

Other Word Forms

• invertebracy noun
• invertebrateness noun

Etymology

Origin of invertebrate

From the New Latin word invertebrātus, dating back to 1820–30. See in- ³, vertebrate

Explanation

An invertebrate is an animal without a backbone. Invertebrate animals include fruit flies and sea sponges. Your backbone allows you to stand up straight, and it also allows you to be grouped with the other vertebrates: animals with backbones. Invertebrates are the opposite: they have no backbone. These are the two major groups of animals. Also, this word is used for people who are spineless in the sense of having no courage. You could say a coward acts in an invertebrate way. Whether it's a backbone-free animal or a courage-free person, all invertebrates lack spines.

Example Sentences

To overcome this bottleneck, researchers launched Ocean Species Discoveries, a data-rich publication platform designed for concise, high-quality marine invertebrate species descriptions.

From Science Daily • Nov. 2, 2025

"It clogs up all that invertebrate life on the bed of the river and it means the fish are not getting the food they require."

From BBC • Sep. 24, 2025

Xu, meanwhile, says that decision-making or desire, hallmarks of autonomy, are not something her invertebrate subjects experience.

From Salon • May 13, 2025

This summer, Austin Hendy, an assistant curator at the Natural History Museum who specializes in invertebrate paleontology, spent hours sifting and sorting through thousands of fossilized shells found in the shell bed.

From Los Angeles Times • Sep. 13, 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

Related Words

• beast
• creature
• pet