noun

• (countable) That which covers or conceals; a cover; something spread or laid over or wrapped about another.
• (uncountable) Action of the verb to cover.
• (topology) A continuous map onto a topological space X, π:E→X, such that there exists a discrete space D and for every x∈X an open neighborhood U⊂X, such that π⁻¹(U)= displaystyle ⨆_(d∈D)V_d and π|_(V_d):V_d→U is a homeomorphism for every d∈D.