"self-acting, moving or acting on its own," 1812 (automatical is from 1580s; automatous from 1640s), from Greek automatos of persons "acting of one's own will;" of things "self-moving, self-acting," used of the gates of Olympus and the tripods of Hephaestus (also "without apparent cause, by accident"), from autos "self" (see auto-) + matos "thinking, animated," *men- (1) "to think."

Of involuntary animal or human actions, from 1748, first used in this sense by English physician and philosopher David Hartley. Meaning "done by self-acting machinery" is by 1850. In reference to a type of firearm, from 1877; specifically of machinery that imitates human-directed action from 1940.

1902, "automatic weapon," from automatic (adj.). Meaning "motorized vehicle with automatic transmission" is from 1949.

"partially automatic," 1853, from semi- + automatic (adj.). In reference to a firearm that loads all or partly by itself (but does not fire continuously) by 1889. As a noun in this sense (short for semi-automatic firearm, etc.) by 1964.

"automated cafeteria," 1903, probably from automatic (adj.), though the system itself is said to have originated in Germany, and the word may be from German. Earlier it meant "an automaton" (1670s).

1837, "to make into an automaton, make into a self-acting machine;" see automaton + -ize. Meaning "to make automatic" attested by 1952 (see automatic (adj.)). Related: Automatized; automatizing.

commercial word-forming element denoting devices that work automatically or businesses containing self-service equipment, abstracted from automat (1903), which probably is from automatic, in which case the element is etymologically from Greek matos "thinking, animated."

Proto-Indo-European root meaning "to think," with derivatives referring to qualities and states of mind or thought.

It forms all or part of: admonish; Ahura Mazda; ament; amentia; amnesia; amnesty; anamnesis; anamnestic; automatic; automaton; balletomane; comment; compos mentis; dement; demonstrate; Eumenides; idiomatic; maenad; -mancy; mandarin; mania; maniac; manic; mantic; mantis; mantra; memento; mens rea; mental; mention; mentor; mind; Minerva; minnesinger; mnemonic; Mnemosyne; money; monition; monitor; monster; monument; mosaic; Muse; museum; music; muster; premonition; reminiscence; reminiscent; summon.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit manas- "mind, spirit," matih "thought," munih "sage, seer;" Avestan manah- "mind, spirit;" Greek memona "I yearn," mania "madness," mantis "one who divines, prophet, seer;" Latin mens "mind, understanding, reason," memini "I remember," mentio "remembrance;" Lithuanian mintis "thought, idea," Old Church Slavonic mineti "to believe, think," Russian pamjat "memory;" Gothic gamunds, Old English gemynd "memory, remembrance; conscious mind, intellect."