Floss/flɑːs/ Definition 1 of 5Pro Tip 1/2Dental Hygiene Flossing daily helps prevent gum disease and tooth decay. My dentist said I should floss every night before bed. Pro Tip 2/2Specific Context 'Floss' as dental thread is mainly used in a dental care context. Do you have any floss? I have something stuck between my teeth.