linkage n.

"to bind, fasten, couple, unite as if by links," late 14c., believed to be from link (n.1), though it is attested earlier. Intransitive sense "become connected, join in marriage" is from 1530s. Related: Linked; linking.

word-forming element in nouns of act, process, function, condition, from Old French and French -age, from Late Latin -aticum "belonging to, related to," originally neuter adjectival suffix, from PIE *-at- (source of Latin -atus, past participle suffix of verbs of the first conjugation) + *-(i)ko-, secondary suffix forming adjectives (see -ic).