"having the power of connecting, serving to connect," 1650s, from connect + -ive (if from Latin, it likely would have been *connexive). Connective tissue is from 1839.
Entries linking to connective
connect v.
mid-15c., "to join, bind, or fasten together," from Latin conectere "join together," from assimilated form of com "together" (see con-) + nectere "to bind, tie" (from PIE root *ned- "to bind, tie").
Displaced 16c. by connex (1540s), from French connexer, from Latin *connexare, a supposed frequentative of conectere (past participle stem connex-). Connect was re-established from 1670s.
A similar change took place in French, where connexer was superseded by connecter. Meaning "to establish a relationship" (with) is from 1881. Slang meaning "get in touch with" is attested by 1926, from telephone connections. Meaning "awaken meaningful emotions, establish rapport" is from 1942. Of a hit or blow, "to reach the target," from c. 1920. Related: Connected; connecting; connectedness.
-ive
word-forming element making adjectives from verbs, meaning "pertaining to, tending to; doing, serving to do," in some cases from Old French -if, but usually directly from Latin adjectival suffix -ivus (source also of Italian and Spanish -ivo). In some words borrowed from French at an early date it has been reduced to -y (as in hasty, tardy).
connectivity n.
"state or degree of connectedness," 1872, from connective + -ity.