cooperative adj.

"the act of working together to one end," 1620s, from French coopération, or directly from Late Latin cooperationem (nominative cooperatio) "a working together," noun of action from past-participle stem of cooperari "to work together," from assimilated form of com "with, together" (see com-) + operari "to work," from PIE root *op- "to work, produce in abundance."

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).