From The Collaborative International Dictionary of English v.0.48:

Thine \Thine\ ([th][imac]n), pron. & a. [OE. thin, AS.
   [eth][imac]n, originally gen. of [eth]u, [eth][=u], thou;
   akin to G. dein thine, Icel. [thorn]inn, possessive pron.,
   [thorn][imac]n, gen. of [thorn][=u] thou, Goth. [thorn]eins,
   possessive pron., [thorn]eina, gen. of [thorn]u thou. See
   Thou, and cf. Thy.]
   A form of the possessive case of the pronoun thou, now
   superseded in common discourse by your, the possessive of
   you, but maintaining a place in solemn discourse, in poetry,
   and in the usual language of the Friends, or Quakers.
   [1913 Webster]

   Note: In the old style, thine was commonly shortened to thi
         (thy) when used attributively before words beginning
         with a consonant; now, thy is used also before vowels.
         Thine is often used absolutely, the thing possessed
         being understood.
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From The Collaborative International Dictionary of English v.0.48:

thou \thou\ ([th]ou), pron. [Sing.: nom. Thou; poss. Thy
   ([th][imac]) or Thine ([th][imac]n); obj. Thee
   ([th][=e]). Pl.: nom. You (y[=oo]); poss. Your (y[=oo]r)
   or Yours (y[=oo]rz); obj. You.] [OE. thou, [thorn]u, AS.
   [eth][=u], [eth]u; akin to OS. & OFries. thu, G., Dan. & Sw.
   du, Icel. [thorn][=u], Goth. [thorn]u, Russ. tui, Ir. & Gael.
   tu, W. ti, L. tu, Gr. sy`, Dor. ty`, Skr. tvam. [root]185.
   Cf. Thee, Thine, Te Deum.]
   The second personal pronoun, in the singular number, denoting
   the person addressed; thyself; the pronoun which is used in
   addressing persons in the solemn or poetical style.
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         Art thou he that should come?            --Matt. xi. 3.
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   Note: "In Old English, generally, thou is the language of a
         lord to a servant, of an equal to an equal, and
         expresses also companionship, love, permission,
         defiance, scorn, threatening: whilst ye is the language
         of a servant to a lord, and of compliment, and further
         expresses honor, submission, or entreaty." --Skeat.
         [1913 Webster]

   Note: Thou is now sometimes used by the Friends, or Quakers,
         in familiar discourse, though most of them corruptly
         say thee instead of thou.
         [1913 Webster]
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