mollusk

American  

[mol-uhsk] / ˈmɒl əsk /

Or mollusc

noun

mollusks plural

1. any invertebrate of the phylum Mollusca, typically having a calcareous shell of one, two, or more pieces that wholly or partly enclose the soft, unsegmented body, including the chitons, snails, bivalves, squids, and octopuses.

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mollusk Scientific  

/ mŏl′əsk /

1. Any of numerous invertebrate animals of the phylum Mollusca, usually living in water and often having a hard outer shell. They have a muscular foot, a well-developed circulatory and nervous system, and often complex eyes. Mollusks include gastropods (snails and shellfish), slugs, octopuses, squids, and the extinct ammonites. Mollusks appear in the fossil record in the early Cambrian Period, but it is not known from what group they evolved.

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Other Word Forms

Derived Forms

• molluscan
  adjective
• molluskan
  adjective
• mollusklike
  adjective

Inflected Forms

Nouns

• mollusks
  plural

Etymology

Origin of mollusk

1775–85; < French mollusque < New Latin Mollusca; see Mollusca

Explanation

Your pet snail, Sammy, is one example of a mollusk, or a soft, spineless animal. In Sammy's case, he has a shell, though some mollusks don't. It's a bit ironic that this term for a large phylum of invertebrates comes from a Latin word that means "soft," mollis, since many mollusks (or molluscs in Britspeak) have hard shells. The epithet comes from the nature of the creatures' bodies, whether in shell (like a snail) or without (like a slug).

Example Sentences

Among them is Veleropilina gretchenae, a newly identified mollusk recovered from the Aleutian Trench at 6,465 meters.

From Science Daily • Nov. 2, 2025

The mollusk lights up using bioluminescence when threatened to distract predators, researchers said.

From Los Angeles Times • Nov. 14, 2024

It wasn’t a worm, a mollusk, or a crustacean.

From Science Magazine • Sep. 21, 2023

The mollusk specialist Alan Solem estimated in 1990 that, of roughly 200 Hawaiian species of one snail family, the Endodontidae, in Honolulu's Bishop Museum, fewer than 40 had been described.

From Salon • May 31, 2023

The really old ones came from the shell of a sea mollusk.

From "The Ear, the Eye, and the Arm" by Nancy Farmer

Related Words

• abalone
• clam
• snail