Merriam-Webster Collegiate Dictionary - thine

 I. adjective  Etymology: Middle English thin, from Old English thin  Date: before 12th century archaic thy — used especially before a word beginning with a vowel or h  II. pronoun, singular or plural in construction  Etymology: Middle English thin, from Old English thin, from thin thy — more at thy  Date: before 12th century archaic that which belongs to thee — used without a following noun as a pronoun equivalent in meaning to the adjective thy; used especially in ecclesiastical or literary language and still surviving in the speech of Friends especially among themselves