RhymeZone: outie definitions

Definitions of outie:

noun: (informal) Anything convex.
noun: (slang) A navel that protrudes from the abdomen.
noun: (childish or euphemistic) A penis, seen as an everted version of a vagina
noun: An extrovert
adjective: Alternative form of outtie [(slang) Out.]

(Definitions from Wiktionary)