mid-15c., "to shut up, enclose, confine," from Latin secludere "shut off, confine," from se- "apart" (see secret (n.)) + -cludere, variant of claudere "to shut" (see close (v.)). Meaning "to remove or guard from public view" is recorded from 1620s. Related: Secluded; secluding.
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).