mid-14c., accioun, "cause or grounds for a lawsuit," from Anglo-French accioun, Old French accion, action (12c.) "action; lawsuit, case," from Latin actionem (nominative actio) "a putting in motion; a performing, a doing; public acts, official conduct; lawsuit, legal action" (source also of Spanish accion, Italian azione), noun of action from past-participle stem of agere "to do" (from PIE root *ag- "to drive, draw out or forth, move").
Spelling with the restored Latin -t- begins in 15c. Meaning "active exertion, activity" is from late 14c. Sense of "something done, an act, deed" is late 14c. Meaning "military fighting" is from 1590s. Meaning "way in which (a firearm, etc.) acts" is from 1845. As a film director's command, it is attested from 1923.
The meaning "noteworthy or important activity" in a modern sense by 1933, as in the figurative phrase a piece of the action (by 1965), perhaps from a sense of action in card-playing jargon by 1914.
No "action" can be had on a bet until the card bet upon appears. If it does not appear after a turn has been made, the player is at liberty to change his bet, or to remove it altogether. Each bet is made for the turn only, unless the player chooses to leave it until he gets some action on it. [from "Faro" in "Hoyle's Games," A.L. Burt Company, New York: 1914]
But there are uses of action as far back as c. 1600 that seem to mean "noteworthy activity." The meaning "excitement" is recorded from 1968. In action "in a condition of effective operation" is from 1650s. Phrase actions speak louder than words is attested from 1731. Action-packed is attested from 1953, originally of movies.
mid-15c., humain, humaigne, "human," from Old French humain, umain (adj.) "of or belonging to man" (12c.), from Latin humanus "of man, human," also "humane, philanthropic, kind, gentle, polite; learned, refined, civilized." This is in part from PIE *(dh)ghomon-, literally "earthling, earthly being," as opposed to the gods (from root *dhghem- "earth"), but there is no settled explanation of the sound changes involved. Compare Hebrew adam "man," from adamah "ground." Cognate with Old Lithuanian žmuo (accusative žmuni) "man, male person."
Human interest is from 1824. Human rights attested by 1680s; human being by 1690s. Human relations is from 1916; human resources attested by 1907, American English, apparently originally among social Christians and based on natural resources. Human comedy "sum of human activities" translates French comédie humaine (Balzac); see comedy.
As an adjective by 1834 in the theological sense "affirming the humanity or human nature of Christ;" by 1855 as "having regard for the broad interests of humanity."
"pertaining to a human being," 1836, from Greek anthrōpikos "human; of or for a man," from anthrōpos "male human being, man" (see anthropo-). Related: Anthropical (1804).
"having human form; anthropoid in form" (of apes, etc.), 1753, Englishing of Late Latin anthropomorphus "having human form," from Greek anthropomorphos "of human form," from anthrōpos "human being" (see anthropo-) + morphē "form," a word of uncertain etymology. Related: Anthropomorphously.