triple check

Noun

 * 1) An extra check or verification made a third time, usually with additional caution or attention.
 * Did you make a double check and a triple check of the entire minefield before proceeding?

Usage notes
This form usually comes after double check, often as a synonym or variant thereof.

Verb

 * 1) To check again; to check with extra caution or attention; to verify or make sure.
 * Did you double check and triple check of the entire minefield before proceeding?

Usage notes
This form usually comes after double check, often as a synonym or variant thereof.