aev

The root aev comes from Latin aevum, "an age, a lifetime, an era" — a stretch of time, whether the span of one life or a whole epoch of history. Greek had a cousin, aiōn ("eon"), and both go back to a shared ancient root meaning "vital force, life span." The English word age itself descends from aevum through Latin aetās and Old French aage — so the most everyday word about time is quietly built on this root.

The family spreads across both meanings of aevum — a personal lifetime and a historical era:

Era / epoch:
- medi- (middle) + aev → medieval: "of the middle age" — the era historians placed between the classical world and the Renaissance.
- co- (together) + aev → coeval: "of the same age" — existing in the same era, contemporary.
- primeval — primus (first) + aev — belonging to the first age, the earliest times.

Lifetime / duration:
- long- (long) + aev → longevity: "long life" — how long something lasts.
- eternal — from aeternus, a contraction of aeviternus ("lasting an age") — stretched all the way out, lasting beyond any single age, forever.

Notice how the root often hides. In eternal you'd never guess the aev is buried inside (aeviternus → aeternus), and in age it has worn down almost beyond recognition. This is the quiet feature of aev: it shaped huge time-words — eternal, medieval, age — while rarely showing its face. Wherever a word reaches across long spans of time, aev is often the engine underneath.