Main Entry: be·ware

Pronunciation: \bi-ˈwer, bē-\

Function: verb

Etymology: Middle English been war, from been to be + war careful — more at be, ware

Date: 14th century

intransitive verb : to be on one's guard <beware of the dog>transitive verb 1 : to take care of <beware your wallet>
2 : to be wary of <we must…beware the exceedingly tenuous generalization — Matthew Lipman>