mid-14c., "cause or grounds for a lawsuit," from Anglo-French accioun, Old French accion (12c.) "action, lawsuit, case," from Latin actionem (nominative actio) "a putting in motion; a performing, doing," noun of action from past participle stem of agere "to do" (see act (v.)). Sense of "something done, an act, deed" is late 14c. Meaning "fighting" is from c.1600. As a film director's command, it is attested from 1923. Meaning "excitement" is recorded from 1968. Phrase actions speak louder than words is attested from 1731.
action ac·tion (āk'shən)
The state or process of acting or doing.
A change that occurs in the body or in a bodily organ as a result of its functioning.
Exertion of force or power.