To double-check means to review something twice, to be sure that no mistakes have been made. When accuracy is extremely important, one may be asked to triple-check data. However, triple-check is not currently a word recognized by the Oxford English Dictionary.

What does double check mean?

If you double-check something, you make certain it is correct or safe, usually by examining it again.

What are the purpose of the double check?

noun Chess. a simultaneous check by two pieces in which the moving of one piece to give check also results in discovering a check by another piece.