What is the meaning of Worth?

To be; to become; to betide; -- now used only in the phrases, woe worth the day, woe worth the man, etc., in which the verb is in the imperative, and the nouns day, man, etc., are in the dative. Woe be to the day, woe be to the man, etc., are equivalent phrases.

Source: Webster’s Revised Unabridged Dictionary (1913), via OPTED