1540s, "separate (someone or something) from a generally body or class of things," from Latin segregatus, past participle of segregare "set apart, lay aside; isolate; divide," literally "separate from the flock," from *se gregare, from se "apart from" (see se-) + grege, ablative of grex "herd, flock" (from PIE root *ger- "to gather").

Originally often with reference to the religious notion of separating the flock of the godly from the sinners, later scientifically in reference to classifications. In modern social context, "to force or enforce racial separation and exclusion," by 1898. Intransitive sense of "separate, go apart" is by 1863. Related: Segregated; segregating.

"the abolition of racial segregation," 1935, American English, from de- "the opposite of" + segregation in the racial sense.

1610s, "act of bringing together the parts of a whole," from French intégration and directly from Late Latin integrationem (nominative integratio) "renewal, restoration," noun of action from past participle stem of Latin integrare "make whole," also "renew, begin again" (see integrate). Anti-discrimination sense (opposed to segregation) is recorded from 1934.

"adherent or advocate of racial segregation," 1915, from segregation + -ist.