1. A fight in which two or more participants punch with their bare hands; a fistfight. A portmanteau of "slug" (meaning "to punch") and "festival." The arguing led to pushing and shoving, which eventually led to an all-out slugfest. She came away from the slugfest with a black eye and a broken hand.

2. A particularly intense or heated argument between two or more people in which points, rebuttals, accusations, etc., are exchanged back and forth. The senator is bracing for a slugfest when she puts her proposal before Congress for a vote. The case has truly been a slugfest between the two large companies' teams of lawyers.