Synonyms of on one's guard in English:

on one's guard

See definition of on guard


1‘police are urging horse owners to be on their guard’

vigilant, alert, on the alert, wary, watchful, cautious, careful, heedful, chary, circumspect, on the lookout, on the qui vive, on one's toes, prepared, ready, wideawake, attentive, observant, keeping one's eyes peeled
informal all ears, beady-eyed, on the ball, not missing a trick, keeping a weather eye on things, cagey, leery
rare regardful, Argus-eyed