Old or discarded articles that are considered useless or of little value. The garage was filled with old junk that needed to be thrown away.
A Chinese sailing vessel with a flat bottom and high stern, often used in East Asia. The harbor was dotted with traditional junks, their sails billowing in the wind.
Slang: illegal narcotic drugs, especially heroin. He was arrested for possession of junk.
Vulgar slang: a man's genitals. He accidentally got kicked in the junk during the match.
Unwanted or unsolicited advertising material, especially in electronic or postal form. My inbox is full of junk that I delete every morning.