This Slang page is designed to explain what the meaning of guts is. The slang word / phrase / acronym guts means . Online Slang Dictionary. A list of slang. guts definition: Noun 1. plural form of gut 2. The entrails or contents of the abdomen. 3. (slang) Courage; determination. 4. (slang) Content, substance. Define gut: guts : the internal organs of an animal — gut in a sentence.