"one of the hereditary social groups of India," 1610s from Portuguese casta "breed, race, caste," earlier casta raça, "unmixed race," from Latin castus "cut off, separated" (also "pure," via notion of "cut off" from faults), past participle of carere "to be cut off from," from PIE *kas-to-, from root *kes- "to cut." Caste system is first recorded 1840. An earlier, now-obsolete sense of caste in English is "a race of men" (1550s), from Latin castus "chaste."
Of the castes, the first three are the natural and gradually established divisions of the Aryan invaders and conquerors of India; the fourth was made up of the subjugated aborigines. The Sanskrit name for caste is varna, color, the different castes having been at first marked by differences of complexion, according to race, and in some degree according to occupation and consequent exposure. [Century Dictionary, 1895]
Meaning "set of correlated principles, facts, ideas, etc." first recorded 1630s. Meaning "animal body as an organized whole, sum of the vital processes in an organism" is recorded from 1680s; hence figurative phrase to get (something) out of one's system (1900). Computer sense of "group of related programs" is recorded from 1963. All systems go (1962) is from U.S. space program. The system "prevailing social order" is from 1806.
library classification system that organizes information into 10 broad areas subdivided numerically into progressively smaller topics, by 1885, named for Melvil Dewey (1851-1931) who proposed it 1876 while acting librarian of Amherst College. He also crusaded for simplified spelling and the metric system.
also mestee, "octoroon, offspring of a white and a quadroon," also, generally, "a half-caste," 1690s, a West Indian word, a corruption of Spanish mestizo (q.v.).
mid-14c., "an exile, a pariah, a person cast out or rejected," literally "that which is cast out," noun use of past participle of Middle English outcasten "to throw out or expel, reject," from out (adv.) + casten "to cast" (see cast (v.)). The adjective is attested from late 14c., "abject, socially despised." The verbal phrase cast out "discard, reject" is from c. 1200. In an Indian context, outcaste "one who has been expelled from his caste" is from 1876; see caste.
heterogeneous people of eastern Burma, 1759 (as Carian), from Burmese ka-reng "wild, dirty, low-caste man" [OED].
"marriage within the tribe or group," 1865, from endo- on model of polygamy. Related: Endogamous (1865). Opposed to exogamy. Apparently both were coined by Scottish anthropologist John Ferguson McLennan (1827-1881) in "Primitive Marriage."
To this law, the converse of caste, forbidding marriage within the tribe, Mr. M'Lennan has given the name of exogamy: while, instead of caste, since that word involves notions unconnected with marriage, he has used the correlative word — endogamy. [review in The Lancet, March 25, 1865]