The word diffuse has two main meanings:

1. To spread out widely or thinly, like how smoke diffuses through a room until it fills every corner. When you open a bottle of perfume, the scent molecules diffuse into the air, spreading gradually until everyone nearby can smell it. Light diffuses through frosted glass, scattering in many directions instead of shining in one focused beam. Scientists study how heat diffuses through materials: touch a metal spoon sitting in hot soup and you'll feel warmth diffusing up the handle toward your fingers.

The word can describe ideas spreading too. When a new slang word diffuses through a school, it starts with one friend group and gradually spreads until everyone's using it. When tension diffuses in an argument, the angry feelings scatter and fade away, like that smoke thinning out until it disappears.

1. As an adjective (pronounced “diff-YOOS”), it means spread out or unfocused. Diffuse lighting in a room comes from many directions rather than one bright lamp. A diffuse explanation rambles across many topics instead of staying focused on the main point. When your ideas feel diffuse, they need gathering and sharpening before they'll make sense to others.