action

First recorded in1300–50; from Latin āctiōn- (stem of āctiō ), equivalent to āct(us) (past participle) + -iōn- replacing Middle English accioun, from Anglo-French, from Latin ; see origin at act, -ion

2. Action, act, deed mean something done. Action applies especially to the doing, act to the result of the doing. An action usually lasts through some time and consists of more than one act: to take action on a petition. An act is single: an act of kindness. Deed emphasizes the finished or completed quality of an act; it may imply an act of some note, good or bad: an irrevocable deed; a deed of daring. 12. See battle¹.

English action comes from Middle English accioun, action, one of whose common meanings is in the legal domain: “a proceeding instituted by one party against another, or the right to bring such a proceeding.” Another common meaning in Middle English is “something done, an act, a deed.” The Middle English noun comes partly from Anglo-French and Old French and partly from Latin āctiō (stem āctiōn- ). Āctiō is formed from āc-, the perfect participle stem of the verb agere, and the noun suffix -tiō, which is used to form abstract nouns from verbs (here expressing action). Latin agere has as many meanings as English do or make. The original meaning of agere was “to drive (cattle, horses, goats, beasts of burden), ride (a horse), drive (a chariot).”
Agere is from the same Proto-Indo-European root, ag- “to drive, lead, bring,” as Greek ágein “to lead, drive,” agōgós “a leader” (as in demagogue and pedagogue ). In Celtic, the participle aktos is the root of ambaktos, ambiaktos “one sent around, ambassador,” adopted from Gaulish into Latin as ambactus “servant, retainer.” Germanic adopted the Celtic word as ambachts “servant” in Gothic, ambacht in Old High German, and, much reduced, Amt “office, authority, post, duty” in German.

Named by analogy with the acronymic names of other agencies, but itself not an acronym