1. noun, slang A shortening of "steroid," referring specifically to anabolic steroids that are used for building muscle mass. Almost exlusively used in the plural. You can't just shoot up roids and get jacked—it still requires a ton or work and dedication! He was thrown out of the professional league for cheating with roids.

2. adjective, slang Used in informal, typically derogatory references to the use or abuse of anabolic steroids (to gain muscle mass). Sometimes hyphenated in such constructions. A lot of people assume I'm some sort of roid head because of the size of my pecs and biceps. Jack flew into a roid-rage when someone spilled his protein shake in the weight room.