We found 2 dictionaries that define the word be on guard:

General (1 matching dictionary)

1. be on guard: Cambridge Advanced Learner's Dictionary

Miscellaneous (1 matching dictionary)

2. be on guard: Idioms

Phrases: be on the safe guard, more... ▸ Words similar to be on guard ▸ Usage examples for be on guard ▸ Idioms related to be on guard ▸ Wikipedia articles (New!) ▸ Words that often appear near be on guard ▸ Rhymes of be on guard ▸ Invented words related to be on guard