Seal - definition of seal by The Free Dictionary
seal 1 (sēl) n. 1. a. A device or material that is used to close off or fasten an opening or connection, especially to prevent the escape of a liquid or gas: used caulk as a seal around the window. b. An airtight closure: a door that lacks a tight seal. c. Something, such as a piece of tape, that is placed on a product or package to show that the ...