- \ \  Latin agere, a verb of great semantic breadth (‘drive, lead, act, do’), has been a prolific source of English words. Its past participle, āctus, produced act, action, active, actor, actual, cachet, and exact, while other parts of its paradigm lie behind agile, agitate, ambiguous, coagulate, cogent, cogitate, examine, exigent, exiguous, and prodigal. Its most obvious offspring, however, are agent (literally ‘(person) doing something’) and agency, formed from the Latin present participial stem agent-. Agere itself is of considerable antiquity, being related to other Indo-European verbs such as Greek ágein ‘drive, lead’, Old Norse aka ‘travel in a vehicle’, and Sanskrit ájati ‘drives’.\ \ Cf.⇒ ACT, AGILE, AMBIGUOUS, CACHET, COGENT, DEMAGOGUE, EXACT, EXAMINE, PRODIGAL
Word origins - 2ed. J. Ayto. 2005.