A wisp is a small, thin, delicate piece of something. You might see a wisp of hair that has escaped from someone's ponytail, curling gently against their cheek. Smoke rises in wisps from a candle you've just blown out, creating those thin, swirling trails that seem to dance in the air before disappearing.

The word suggests something fragile and fleeting. A wisp of cloud might stretch across an otherwise clear blue sky. A wisp of steam rises from a cup of hot chocolate. When something appears in wisps, it's usually so thin and light that it seems barely there at all.

Wisp can also describe a small, slight person, especially when you want to emphasize how thin or delicate they seem: “She was just a wisp of a girl.” The word carries a sense of something that might vanish or blow away at any moment, like a will-o'-the-wisp, which is a mysterious light that supposedly appears at night in marshes and leads travelers astray, flickering and disappearing like smoke.