What does mollusc mean?
A mollusc is one of the soft-bodied invertebrate animals that make up the phylum Mollusca. Despite their name, not every mollusc has a visible shell: the group includes snails and clams with shells, slugs without them, and cephalopods such as octopuses and squids. Most molluscs live in water, although several terrestrial species, including slugs and snails, live on land. The word is used particularly in biology, ecology, palaeontology, and natural-history writing, where it provides a useful collective term for animals that may otherwise look very different. In British English, “mollusc” is the standard spelling; American English more often uses “mollusk.” The word comes from Latin and ultimately refers to the animals' soft bodies, although many species also produce shells or other hard structures for protection.
nounA mollusc is a soft-bodied invertebrate animal, typically protected by a shell, belonging to the phylum Mollusca. The group includes snails, slugs, clams, oysters, squids, and octopuses.
- Any soft-bodied invertebrate belonging to the phylum Mollusca, often having a shell or a hard internal structure.
"The aquarium displays a remarkable variety of molluscs from the world's coral reefs."
"Marine biologists study the distribution of molluscs along the rocky coastline."
"She collected a variety of colourful mollusc shells on the beach."
The usual plural is “molluscs” in British English and “mollusks” in American English.
"The museum preserves shells and fossils of molluscs from several geological periods."
From Latin for “soft,” molluscs include animals as different as garden slugs, octopuses, and giant clams.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of mollusc
The word entered English in the late 16th century from Latin mollusca, a plural form used for a class of soft-bodied animals. The Latin term derives from mollusca, from mollis, meaning “soft,” related to the same root that appears in words such as mollification. The related North American spelling “mollusk” reflects the same Latin source, while the English derivatives “molluscan” and “molluscous” preserve the word's scientific associations.
Related word forms
How mollusc is actually used
The term is formal and scientific, though it is also used in natural-history and educational contexts. In American English, “mollusk” is generally preferred.
Easily confused with mollusc
“Mollusc” and “mollusk” refer to the same group of animals; “mollusc” is the standard British spelling, whereas “mollusk” is the most common American spelling.