Merriam Webster differs: You -- Middle English, from Old English ēow, dative & accusative of gē you; akin to Old High German iu, dative of ir you, Sanskrit yūya

Merriam Webster differs: You -- Middle English, from Old English ēow, dative & accusative of gē you; akin to Old High German iu, dative of ir you, Sanskrit yūyam you First Known Use: before 12th century Thou -- Middle English, from Old English thū; akin to Old High German dū thou, Latin tu, Greek sy First Known Use: before 12th century So "thou" is cognate with German "du", and "you" is related to German "ihr", the plural of "sie", if I'm understanding this correctly.