co-occurrence (n.)

A term used in LINGUISTICS and PHONETICS to refer to the permitted SYNTAGMATIC combination of UNITS, according to the GRAMMATICAL and LEXICAL RULES of a LANGUAGE. For example, a co-occurs with boy, but not with information; eke co-occurs with out, but not with in. The CONSTRAINTS involved are known as co-occurrence relations or restrictions, and are often specified in the form of CONTEXT-sensitive or TACTIC rules. The dependencies involved may be unidirectional (e.g. ADVERBS co-occurring with VERBS, but not necessarily the other way round), bidirectional (e.g. TRANSITIVE verbs and OBJECTS), and mutually exclusive (e.g. a cannot co-occur with an in the same NOUN PHRASE).