A condition that occurs when one wears headphones for an extended period of time, forcing the hair on the center of one's head to be pressed down, creating the appearance of a dent in the center of one's head.
1. the melding of the words headphone and astronaut
2. Someone who listens to music (some would say in excess) on their (often high quality) headphones, often associated with persons into the more atmospheric and trip hop styles of the electronica genre. These persons are often engrossed with 1 or more elements of the music such as production, layering, nuances of sound, etc. and often lean towards introversion.
3. a trip hop group from MS (US)