(DoD, NATO) Any process carried out by one unit or person with the object of ascertaining the friendly or hostile character or identity of another. See also countersign; password.
Department of Defense Dictionary of Military and Associated Terms. 31 January 2011.
| APA | Military Dictionary (DoD). (2011). challenge. Retrieved September 22, 2026, from http://smartdefine.org/challenge/definitions/1960722 |
| Chicago | Military Dictionary (DoD). 2011. "challenge" http://smartdefine.org/challenge/definitions/1960722 (accessed September 22, 2026). |
| Harvard | Military Dictionary (DoD) 2011, challenge, Smart Define, viewed 22 September, 2026, <http://smartdefine.org/challenge/definitions/1960722>. |
| MLA | Military Dictionary (DoD). "challenge" 4 April 2011. Web. 22 September 2026. <http://smartdefine.org/challenge/definitions/1960722> |