The term BE OFF GUARD can be summarized as being unprepared or unaware of a situation. The crossword solutions for this term are NAP (3 letters) and NAPS (4 letters). NAP is an acronym for Non-Alerted Posture, which is a military term used to describe a state of readiness in which troops are not expecting an attack. NAPS is an acronym for Non-Alerted Posture System, which is a system used by the military to monitor the readiness of troops.