Define tab. tab synonyms, tab pronunciation, tab translation, English dictionary definition of tab. n. 1. A projection, flap, or short strip attached to an object to facilitate opening, handling, or identification. 2. A small, usually decorative flap or, Definition of tab noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more., a small flap, strap, or loop, as on a piece of clothing, used for pulling, hanging, or decoration: tabs on the jacket collar. a small projection from a card or folder, used as an aid in filing: The tab on the file folder was labeled "Top Secret.'' check: She promised to pick up (= pay) the tab for dinner., Tab definition: A projection, flap, or short strip attached to an object to facilitate opening, handling, or identification., A tab is an attached flap or piece of material. You use a metal tab to open a can of soda, and you might use plastic tabs to separate sections in your binder., (in a web browser window or in a spreadsheet or other application) a page displayed by clicking on or selecting a user interface element that resembles a paper tab. The third tab in the spreadsheet list expenses..