off guard

Idioms and Phrases

Also, off one's guard . Not watchful, easily surprised. It is often put as catch (or be caught) off guard , meaning “take (or be taken) by surprise.” For example, The securities analyst was caught off guard by that financial report , or With any luck the boss will be off guard when I come in late . [Late 1600s] The antonym, on guard or on one's guard , meaning “watchful or prepared, especially to defend oneself,” was first recorded in 1577. For example, In this crowd we must be on guard against pickpockets , or I'm always on my guard when I'm asked how I voted .