Breakeven

The level at which a position returns exactly nothing. For a long call it is the strike plus the premium paid.

Where this comes up

Lessons that use the term in context, which is usually more useful than the definition on its own.

Vertical spreads — Capping both ends on purpose, and what it costs.
The arithmetic of a drawdown — Why a 50% loss needs a 100% gain, and what that means for size.