mid-15c., militari, "pertaining to or befitting soldiers; used, done, or brought about by soldiers," from Old French militaire (14c.) and directly from Latin militaris "of soldiers or war, of military service, warlike," from miles (genitive militis) "soldier," a word of unknown origin.
Perhaps ultimately from Etruscan, or else meaning "one who marches in a troop," and thus connected to Sanskrit melah "assembly," Greek homilos "assembled crowd, throng." De Vaan writes, "It is tempting to connect mīlia [pl.] 'thousand(s)', hence *mīli-it- 'who goes with/by the thousand' ...." Related: Militarily. Old English had militisc, from Latin.
Military police is from 1827. Military age, at which one becomes liable to military service, is by 1737. Military-industrial complex was coined 1961 in the farewell speech of U.S. president Dwight D. Eisenhower.
"soldiers generally," 1757, from military (adj.); commonly only with the definite article. Earlier, "a military man" (1736).
mid-14c., enginour, "constructor of military engines," from Old French engigneor "engineer, architect, maker of war-engines; schemer" (12c.), from Late Latin ingeniare (see engine); general sense of "inventor, designer" is recorded from early 15c.; civil sense, in reference to public works, is recorded from c. 1600 but not the common meaning of the word until 19c (hence lingering distinction as civil engineer). Meaning "locomotive driver" is first attested 1832, American English. A "maker of engines" in ancient Greece was a mekhanopoios.
1818, "act as an engineer," from engineer (n.). Figurative sense of "arrange, contrive, guide or manage (via ingenuity or tact)" is attested from 1864, originally in a political context. Related: Engineered. Middle English had a verb engine "contrive, construct" (late 14c.), also "seduce, trick, deceive" (c. 1300) and "put to torture."
1720, "work done by an engineer," from engineer (n.). As a field of study, attested from 1792. An earlier word was engineership (1640s); engineery was attempted in 1793, but it did not stick.
German manufacturing company, named for founder Max Braun, mechanical engineer in Frankfurt am Main (1921).
type of rotary internal combustion engine, 1961, from name of German engineer Felix Wankel (1902-1988).
electronic musical instrument, 1927, from the name of its inventor, Russian engineer Léon Thérémin (1896-1993).