thine
pron.pron. an old-fashioned way to say 'yours'. You use it when talking to one person, especially in very old books, poems, or prayers.
pron. the archaic second-person singular possessive pronoun. Used as a predicative form of 'thy' or as an attributive form before a word beginning with a vowel sound.
All that I have is thine.
In the old text, the knight says to the king that his sword and his life are thine.
The poet uses 'thine' instead of 'thy' before the word 'eyes' to create a smoother transition between the vowel sounds, a common practice in Early Modern English verse.
From Middle English thyn, þyn, from Old English þīn, from Proto-West Germanic þīn, from Proto-Germanic þīnaz. Cognate to German dein, Danish, Swedish and Norwegian din, Faroese tín and Icelandic þinn.
Archaic; functions as the possessive case of 'thou'. It is used either as a possessive pronoun ('it is thine') or as a possessive adjective before a vowel ('thine eyes').