noun
shellfish
SHEL-fish/ˈʃelfɪʃ/
An aquatic invertebrate with a shell, often eaten as seafood.
The crab and mussel are shellfish protected by hard outer coverings.

Etymology
Shell combines with fish in its older, broader sense of any aquatic animal. The name therefore describes a water-dwelling animal with a shell, rather than requiring it to be a fish in the narrower modern sense.
In context
So is this neurotoxin present in Florida seafood? Yes, in both freshwater fish and shellfish – oysters and bass, etc., and out into the bay.
More examples
- The restaurant serves fresh shellfish with lemon and butter.
- Crabs are shellfish with hard outer coverings and jointed legs.
- She checks local warnings before gathering shellfish along the shore.
Forms
shellfish · shellfishes
Similar words
- crustacean
- Specifically an animal with a jointed outer skeleton, like a crab.
- mollusk
- A soft-bodied invertebrate; some lack shells or live on land.