Swaddlemouth Share definition Flag An insult. A term to call prepubescent minors (or immature adults) when they think they’re being slick/sneaky with their words when they’re not. “Shut your swaddlemouth, you baby!”“I got in trouble for acting swaddlemouthed with my mom…” Swaddlemouth by Maverick ㍃ March 2, 2022 Get the Swaddlemouth mug.