early 15c., casuelte, caswelte, "chance, accident; incidental charge," from casual (adj.) on the model of royalty, penalty, etc. From the earliest use especially of untoward events or misfortunes. The meaning "losses in numbers from a military or other troop" is from late 15c. The meaning "an individual killed, wounded, or lost in battle" is from 1844. Casuality had some currency 16c.-17c. in the sense "chance, a chance occurrence," especially an unfortunate one, but now is obsolete.
"done by automatic equipment," 1952, American English, adjective based on automation.
1961, member of the U.S. anti-communist John Birch Society, which was founded 1958 and named for John Birch, U.S. Baptist missionary and Army Air Forces captain killed by Chinese Communists shortly after the end of World War II, who is considered the first American casualty of the Cold War.
late 15c., pariel, "rope or chain that fixes the middle of a yard to a mast," from parel "equipment" (c. 1400), earlier "apparel" (early 14c.), a shortening of apparel (n.).
c. 1300, "personal fighting equipment, body armor," also "armor or trappings of a war-horse," from Old French harnois, a noun of broad meaning: "arms, equipment; harness; male genitalia; tackle; household equipment" (12c.), of uncertain origin, perhaps from Old Norse *hernest "provisions for an army," from herr "army" (see harry (v.)) + nest "provisions" (see nostalgia). Non-military sense of "fittings for a beast of burden" is from early 14c. German Harnisch "harness, armor" is the French word, borrowed into Middle High German. The Celtic words are believed to be also from French, as are Spanish arnes, Portuguese arnez, Italian arnese. Prive harness (late 14c.) was a Middle English term for "sex organs."