1530s, "to mock" (transitive, now obsolete), from French alluder or directly from Latin alludere "to play, make fun of, joke, jest," also of waves lapping the shore, from assimilated form of ad "to" (see ad-) + ludere "to play" (see ludicrous). Meaning "make an indirect reference, point in passing" is from 1530s. Related: Alluded; alluding.
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/allusive">Etymology of allusive by etymonline</a>
Harper, D. (n.d.). Etymology of allusive. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/allusive