mollusk

American  

[mol-uhsk] / ˈmɒl əsk /

Or mollusc

noun

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

• molluscan
  adjective
• molluskan
  adjective
• mollusklike
  adjective

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

Today she listens to me rant about my slimy mollusk phobia, and I push back against her competitive streak with my own.

From Los Angeles Times • Jan. 9, 2026

Porosity is known to affect the structural integrity of mollusk shells, making shells weaker and potentially more susceptible to damage.

From Science Daily • Apr. 17, 2024

The boy’s family in rural Edmond, Oklahoma, humored him with toy versions of an eight-legged mollusk, but as Cal got older it became clear that only the real thing would do.

From Seattle Times • Apr. 15, 2024

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

From Science Magazine • Sep. 21, 2023

Decades later, it was found by scientists, who marveled at the appearance of this perfectly preserved ocean mollusk in the middle of a desert.

From "The Long-Lost Home" by Maryrose Wood

Related Words

• abalone
• clam
• snail