Be on one's guard; be cautious or wary about; be alert to:
— Beware of telephone salesmen.

synonym: mind.

Roget 668: warn, caution; forewarn, prewarn^†; admonish, premonish^†; give notice, give warning, dehort^†; menace etc. (threaten) 909; put on one's guard; sound the alarm etc. 669; croak.    beware, ware; take warning, take heed at one's peril; keep watch and ward etc. (care) 459.    ... show more

Dutch: zich hoeden, oppassen