A lid or mechanical seal, usually one that completely closes the object
Album cover (see also: CD and DVD packaging);
Book cover or magazine cover;
Cover (philately), generic term for envelope or package;
;
Something that conceals something else:
Cover (intelligence), the purported occupation or purpose of a spy
Undercover;
;
Cover (military), a form of protection in combat;
Cover (telecommunications), a communications concealment technique;
Mating of animals, e.g. a horse covers a mare;
Incubation of eggs;
Cover (geology) or sedimentary cover, overlies a basement (geology) or crystalline basement;
;
Cover (film), a 2007 film directed by Bill Duke;
Cover charge, an entry fee;
Cover (law), a remedy for the breach of a contract for the receipt of goods;
Cover version, a new version of a previously recorded song
Cover band, a musical band that plays only cover versions;
;
Cover (topology), the mathematical concept of a collection of subsets of a set whose union is the whole set;
Cover, a fielding position in cricket;
Covering space, in the theory of Riemann surfaces and topology;
Cover (finance), repurchasing a short order made on the stock/equity, forex or futures markets;
Cover 2, a class of defensive play in American Football;
Cover (unit), an area approximately equal to 2698 square metres;
Cover (database theory), an equivalent set of constraints in database theory;