h₂eyg-eyo-
“to keep driving forward, urging”agile, agitate, ambiguity
Iterative yielding Latin agitāre, English agile, agitate, ambiguity.
Discussion
The iterative form *h₂eyg-eyo- derives from Proto-Indo-European *h₂eyg- ("to drive, to move with force"). The *-eyo- suffix marks sustained or repeated action, and this iterative force echoes through the extraordinary number of descendants in the Western languages. In Latin, the root produced agere ("to do, to drive, to lead, to act"), one of the most productive verbs in the language, whose past participle āctus alone generated English act, action, and active. The derivatives include: agent ("one who drives or acts"), agile ("capable of being driven quickly"), and agitate ("to drive repeatedly"). Ambiguous (from ambigere, "to drive in two directions") captures the state of being driven both ways at once. Essay derives from Latin exagium ("a weighing, a trial"), through Old French essai, reflecting the sense of driving out or testing. Examine comes from exāmināre, where the driving-forth sense became one of testing and scrutiny. Exigent (from exigere, "to drive out, to demand") preserves the forceful demand implicit in the iterative. Greek ágō (ἄγω, "to lead, to drive") connects to the same root with regular loss of the initial laryngeal. The semantic field of *h₂eyg- is one of directed force applied to persons, animals, ideas, and inquiries alike. What unites the agent who acts, the examiner who probes, the essayist who weighs, and the agitator who stirs is the original Proto-Indo-European image of driving forward — a force applied continuously to move something from where it is to where it must go.