What does hast thou mean?

The phrase "hast thou" is an archaic form of the second person singular pronoun "you" used as the subject of a verb in English. It combines the Old English word "hafast" (meaning "you have") and the pronoun "thou." This form was commonly used in English throughout the Middle Ages and the Early Modern English period, but it gradually fell out of use during the 18th century and is rarely found in modern English except in highly formal or literary contexts.