early 15c., "lavish, extravagant, liberal to excess," from Latin profusus "spread out, lavish, extravagant," literally "poured forth," past-participle adjective from profundere "pour forth," from pro "forth" (from PIE root *per- (1) "forward") + fundere "to pour" (from nasalized form of PIE root *gheu- "to pour"). Meaning "bountiful, abundant, copious" is from c. 1600. Related: Profusely; profuseness.
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).
<a href="https://www.etymonline.com/word/profusive">Etymology of profusive by etymonline</a>
Harper, D. (n.d.). Etymology of profusive. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/profusive