1560s, "debate, discussion" (on the notion of "a mental tossing to and fro"), from French agitation, from Latin agitationem (nominative agitatio) "motion, agitation," noun of action from past-participle stem of agitare "move to and fro," frequentative of agere "to set in motion, drive forward; keep in movement" (from PIE root *ag- "to drive, draw out or forth, move").
The physical sense of "state of being shaken or moving violently" is from 1580s; the meaning "state of being mentally agitated" is from 1722; that of "arousing and sustaining public attention" to some political or social cause is from 1828. Old English glossed Latin agitatio with unstilnis.
Proto-Indo-European root meaning "to drive, draw out or forth, move."
It forms all or part of: act; action; active; actor; actual; actuary; actuate; agency; agenda; agent; agile; agitation; agony; ambagious; ambassador; ambiguous; anagogical; antagonize; apagoge; assay; Auriga; auto-da-fe; axiom; cache; castigate; coagulate; cogent; cogitation; counteract; demagogue; embassy; epact; essay; exact; exacta; examine; exigency; exiguous; fumigation; glucagon; hypnagogic; interact; intransigent; isagoge; litigate; litigation; mitigate; mystagogue; navigate; objurgate; pedagogue; plutogogue; prodigal; protagonist; purge; react; redact; retroactive; squat; strategy; synagogue; transact; transaction; variegate.
It is the hypothetical source of/evidence for its existence is provided by: Greek agein "to lead, guide, drive, carry off," agon "assembly, contest in the games," agōgos "leader," axios "worth, worthy, weighing as much;" Sanskrit ajati "drives," ajirah "moving, active;" Latin actus "a doing; a driving, impulse, a setting in motion; a part in a play;" agere "to set in motion, drive, drive forward," hence "to do, perform," agilis "nimble, quick;" Old Norse aka "to drive;" Middle Irish ag "battle."
late 14c., "violent movement or agitation, emotional disturbance," from Old French commocion "violent motion, agitation" (12c., Modern French commotion) and directly from Latin commotionem (nominative commotio) "violent motion, agitation," noun of action from past participle stem of commovere "to move, disturb," from com "with, together," perhaps here "thoroughly" (see com-) + movere "to move" (from PIE root *meue- "to push away").
From mid-15c. as "public unrest or disturbance." Verbs commote "to disturb, stir up" (1852), commove (late 14c.) are marked "rare" in Century Dictionary.
"calm, tranquil, free from disturbance or agitation," c. 1600, past-participle adjective from compose (v.). Earlier (1560s) "made up of parts." Related: Composedly; composedness.
1726, "a drawing or gathering into folds or wrinkles," from pucker (v.). In 18c.-19c. sometimes also in a figurative sense, "state of agitation, condition of excitement" (1741).
"Public agitation for greater safety and higher quality in consumer goods" [OED], 1969, in reference to the concerns and methods of U.S. lawyer and consumer advocate Ralph Nader (b. 1934) + -ism.