Noun

1. An irregular line left from smearing or motion.

   The picture I took out the car window had streaks.

2. A continuous series of like events.

   I hope I can keep up this streak of accomplishments.

3. The color of the powder of a mineral. So called, because a simple field test for a mineral is to streak it against unglazed white porcelain.
4. A moth of the family Geometridae Chesias legatella (see Streak (moth)).
5. A tendency or characteristic, but not a dominant or pervasive one.

   She's a quiet, bookish person, but she has a rebellious streak.

Verb

1. to have or obtain streaks.

   If you clean a window in direct sunlight, it will streak.

2. to run naked in public

   It was a pleasant game until some guy went streaking across the field.

3. to create streaks

   You will streak a window by cleaning it in direct sunlight.

4. To move very swiftly.