verb

• (transitive) To question someone after a military mission in order to obtain information (especially intelligence).
  "But, for whatever combination of reasons - and, to be fair, he'd been blasted in the face by shrapnel, was probably badly concussed, and, indeed, would actually remember nothing from the battle after he'd been hit when he was later debriefed - aside from two destroyers left behind to help Hiei, the rest of the Japanese forces withdrew north just before 0300 in the morning."
• (transitive) To question someone, or a group of people, after the implementation of a project, in order to learn from mistakes, etc.
• (transitive) To inform subjects of an experiment about what has happened in a complete and accurate manner.