Risk

Hit rate

The proportion of trades that make money. On its own it tells you almost nothing, which is why it is the number most often quoted.

Where this comes up

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

Expectancy over a hundred trades — Hit rate and reward-to-risk, turned into one number.
The arithmetic of a drawdown — Why a 50% loss needs a 100% gain, and what that means for size.
Risk of ruin — The probability nobody calculates before they need it.