egg·shell / ˈegˌshel/ • n. the thin, hard outer layer of an egg, esp. a hen's egg. ∎ used in similes and metaphors to refer to the fragile nature of something: the truck would crush his car like an eggshell. ∎ (also eggshell paint) an oil-based paint that dries with a slight sheen: the woodwork was painted in eggshell. ∎ a pale yellowish-white color.