A tress is a long lock or strand of hair, especially when it's flowing, wavy, or beautifully arranged. The word usually refers to human hair and often appears in its plural form, tresses.

You might read in a story about a princess with “golden tresses” cascading down her back, or hear someone describe flowing tresses blowing in the wind. The word carries a poetic, elegant feeling: you wouldn't usually say someone has nice tresses after a regular haircut, but you might describe the long, flowing hair in a classical painting that way.

While it's not a word people use much in everyday conversation (you'd more likely just say “hair”), you'll encounter it frequently in literature and stories, where it adds a touch of beauty and old-fashioned elegance to descriptions.