WordWeight : Weighing the Words

Pronunciation : Thine
Part of Speech : pron.
Etymology : [OE. thin, AS. edhin, originally gen. of edhu, edhu, thou; akin to G. dein thine, Icel. ?inn, possessive pron., ?in, gen. of ?u thou, Goth. ?eins, possessive pron., ?eina, gen. of ?u thou. See Thou, and cf. Thy.]
Definition : Defn: A form of the possessive case of the pronoun thou, now superseded in common discourse by your, the possessive of you, but maintaining a place in solemn discourse, in poetry, and in the usual language of the Friends, or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.

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.

& a.
Source : Webster's Unabridged Dictionary, 1913