1. Something you shit out, you can get big ones, runny ones or little pellet things (can be hard to flush). 2. Term of abuse, as in: "That Hitler was a real poo." 3. sometimes with the suffix 'f', meaning a gay man. (Shak) A poo, a poo, my kingdom for a poo. Endlessly amusing especially if you're a boy or if you spell all day long writing boring fucking dictionary definitons.