means A loud, fast, defiantly raw style of rock music (and its associated anti-authority subculture and fashion), or more loosely a young hoodlum, troublemaker, or worthless person.

from "Punk" surfaces in English around the 17th century meaning a prostitute, and soon also rotten or decayed wood — the soft, crumbling kind that smolders and was used as tinder. From "worthless, rotten" the word drifted to mean a worthless person or petty criminal, and by the 20th century a contemptible young upstart. The musical sense was pinned on by 1970s rock critics who took the existing slur — punk as cheap, snotty, no-good — and wore it like a badge. The deeper roots are murky; no one's certain where the original "punk" came from.