having or forming a boundary or barrier: He was blocked by a closed door. The house had a closed porch.

brought to a close; concluded: It was a closed incident with no repercussions.

not public; restricted; exclusive: a closed meeting; a closed bid at a private auction.

not open to new ideas or arguments.

self-contained; independent or self-sufficient: a closed, symbiotic relationship.

Phonetics. (of a syllable) ending with a consonant or a consonant cluster, as has, hasp.Compare open(def 35b).

Linguistics. (of a class of items) limited in membership and not readily expanded to include new items, as the class of inflectional affixes, articles, pronouns, or auxiliaries (opposed to open).

Hunting, Angling. restricted as to the kind of game that may be legally taken and as to where or when it may be taken: woods closed to deer hunters.

Mathematics.

(of a set in which a combining operation between members of the set is defined) such that performing the operation between members of the set produces a member of the set, as multiplication in the set of integers.

(of an interval) containing both of its endpoints.

(of a map from one topological space to another) having the property that the image of a closed set is a closed set.

(of a curve) not having endpoints; enclosing an area.

(of a surface) enclosing a volume.

(of a function or operator) having as its graph a closed set.

Origin of closed

Middle English word dating back to 1175–1225; see origin at close, -ed^{2}

Related formshalf-closed, adjectivesem·i·closed, adjectivewell-closed, adjective

(of a curve or surface) completely enclosing an area or volume

(of a set) having members that can be produced by a specific operation on other members of the same setthe integers are a closed set under multiplication

c.1200, past participle adjective from close (v.). Closed circuit is attested from 1827; closed shop in union sense from 1904; closed system first recorded 1896 in William James.