erg

The root erg comes from Greek ergon, meaning "work" — not work in the boring sense of chores, but work as the Greeks saw it: a force doing something, action producing an effect. A blacksmith hammering metal, a runner straining forward, a chemical reaction firing off — all of these were ergon, work in motion.

The most important child of this root is energy. Greek en- (in, within) + ergon (work) = energeia, literally "the work that is inside" — the inner power that lets something act. Aristotle used the word for a thing's active force, the difference between potential and actually-doing. That's exactly what energy still means today: the capacity to do work. From it English built energetic (full of inner work, bursting with activity) and energize (to put the inner work into something — to charge it up). The physics unit erg, a tiny measure of mechanical work, is named straight off the bare root.

Watch how a prefix changes what kind of work:

- syn- (together) + ergon → synergy: two forces working together so the combined effect beats the sum of the parts. The adjective is synergic — describing things that pull in the same direction.
- metal + ergon → metallurgy: the working of metal — extracting it from ore, smelting it, shaping it. The blacksmith's craft turned into a science.
- allos (Greek "other") + ergon → allergy: an "other-working," an altered reaction. A doctor coined it in 1906 for the body reacting in the wrong, abnormal way to a harmless substance.

Notice the pattern: erg always points to work or action, and the prefix tells you whose work, what kind, or how it's gone wrong. Inner work → energy. Joint work → synergy. Metal work → metallurgy. Wrong work → allergy.

One family link worth knowing: ergon is a cousin of Greek organon ("tool, instrument"), the source of organ — a tool is simply the thing you do work with. And far across the language family, erg is a distant relative of the plain Germanic word work itself; both trace back to the same ancient root meaning "to do."