exclusion n.

word-forming element, in English meaning usually "out of, from," but also "upwards, completely, deprive of, without," and "former;" from Latin ex "out of, from within; from which time, since; according to; in regard to," from PIE *eghs "out" (source also of Gaulish ex-, Old Irish ess-, Old Church Slavonic izu, Russian iz). In some cases also from Greek cognate ex, ek. PIE *eghs had comparative form *eks-tero and superlative *eks-t(e)r-emo-. Often reduced to e- before -b-, -d-, -g-, consonantal -i-, -l-, -m-, -n-, -v- (as in elude, emerge, evaporate, etc.).

(klōz), c. 1200, "to shut, cover in," from Old French clos- (past participle stem of clore "to shut, to cut off from"), 12c., from Latin clausus, past participle of claudere "to shut, close; to block up, make inaccessible; put an end to; shut in, enclose, confine" (always -clusus, -cludere in compounds), from PIE root *klau- "hook," also "peg, nail, pin," all things used as locks or bolts in primitive structures.

Also partly from Old English beclysan "close in, shut up." Intransitive sense "become shut" is from late 14c. Meaning "draw near to" is from 1520s. Intransitive meaning "draw together, come together" is from 1550s, hence the idea in military verbal phrase close ranks (mid-17c.), later with figurative extensions. Meaning "bring to an end, finish" is from c. 1400; intransitive sense "come to an end" is from 1826. Of stock prices, from 1860. Meaning "bring together the parts of" (a book, etc.) is from 1560s. Related: Closed; closing.

"tending to exclude," 1817, from exclusion + -ary.