Meaning of “shell” - Learner’s Dictionary

shell

noun [ C ] uk us /ʃel/
COVERING

B2 the hard outer covering of some creatures and of eggs, nuts, or seeds:

a snail's shell
an egg shell
BOMB

a bomb fired from a large gun

→ See also sea shell

(Definition of “shell noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)