Definitions of punk:

noun: substance that smolders when ignited; used to light fuses (especially fireworks)
noun: rock music with deliberately offensive lyrics expressing anger and social alienation; in part a reaction against progressive rock
noun: a teenager or young adult who is a performer (or enthusiast) of punk rock and a member of the punk youth subculture
noun: an aggressive and violent young criminal
noun: material for starting a fire
adjective: of very poor quality