Firmness is the quality of being solid, steady, or unwavering. When you press on a ripe apple, it might feel soft and mushy, but a fresh one has firmness: it holds its shape and resists your touch. A firm mattress doesn't sink down when you lie on it, and firm ground stays solid underfoot instead of turning to mud.

The word also describes strength of character or resolve. A teacher who maintains firmness doesn't change the classroom rules because of whining or complaints. When your parents show firmness about bedtime, they mean what they say and stick to it, even if you try to negotiate. This kind of firmness isn't about being mean or rigid: it's about having clear principles and following through with decisions.

You can hear firmness in someone's voice when they speak with confidence and certainty, without hesitation or doubt. A coach might address the team with firmness before an important game, making everyone understand that practice starts on time and everyone needs to give their best effort. Firmness combines strength with steadiness, whether you're talking about physical objects that resist pressure or people who stand by their decisions.