Twofold means two times as much, or having two parts or aspects. When something increases twofold, it doubles. If your allowance was five dollars and it becomes twofold, you now get ten dollars.

The word often describes situations where something has two distinct elements. A plan might have a twofold purpose: to raise money for the school and to bring the community together. A problem could present a twofold challenge: it's both difficult to understand and hard to solve.

You'll see twofold used when people want to emphasize that something is double or has two important dimensions. A scientist might report that a medicine had a twofold effect, helping patients in two different ways. A coach might explain that practice has a twofold benefit, improving your skills while building your confidence.

Twofold sounds more formal than simply saying “double” or “two ways,” which makes it useful when you want to sound thoughtful and precise about what you're describing.