ETYM Old Eng. alas, allas, Old Fren. alas, French hélas; a interj. (Latin ah.) + las wretched (that I am), Latin lassus weary, akin to Eng. late. Related to Late.
An exclamation expressive of sorrow, pity, or apprehension of evil; -- in old writers, sometimes followed by day or white; alas the day, like alack a day, or alas the white.