1. A membranous fold of skin or mucous membrane that supports or restricts the movement of a part or organ; such as, the small band of tissue that connects the underside of the tongue to the floor of the mouth.
2. Small pieces of pink colored skin that attach your lips, cheeks, and tongue to a person's mouth.
3. A narrow reflection, or fold, of mucous membrane passing from a more fixed to a movable part, serving to check undue movement of the part; an anatomical structure resembling such a fold.