mid-15c., "to undervalue, under-rate," from Latin depretiatus, past participle of depretiare "to lower the price of, undervalue," from de "down" (see de-) + pretium "price" (see price (n.)). From 1640s in transitive sense of "lessen the value of, to lower in value." Intransitive sense of "to fall in value, become of less worth" is from 1790. Related: Depreciated; depreciating.
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/depreciative">Etymology of depreciative by etymonline</a>
Harper, D. (n.d.). Etymology of depreciative. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/depreciative