Meaning of CLOSED in English

CLOSED

■ adjective

1》 not open or allowing access.

↘not open to all: the UN Security Council met in ~ session.

2》 not communicating with or influenced by others: a ~ society.

3》 Mathematics (of a set) having the property that the result of a specified operation on any element of the set is itself a member of the set.

4》 Geometry (of a curve or figure) formed from a single unbroken line.

5》 Phonetics (of a syllable) ending in a consonant.

Phrases

behind ~ doors taking place secretly.

a ~ book a subject or person about which one knows nothing.

Concise Oxford English vocab.      Сжатый оксфордский словарь английского языка.