: a small, flat piece on a box, envelope, etc., that can be put into a hole in order to hold two parts together
: a small, flat piece that sticks out from the edge of something (such as a folder) and allows you to identify and find it easily
: a small piece of metal, plastic, etc., that is pulled in order to open or close something
: to put a small, identifying label (called a tab) on something
: to say that (someone or something) will do something or have a particular role or purpose
: to hit the tab key on a computer or typewriter
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