You \You\ ([=u]), pron. [Possess. Your ([=u]r) or Yours ([=u]rz); dat. & obj. You.]

[OE. you, eou, eow, dat. & acc., AS. e['o]w, used as dat. & acc. of ge, g[=e], ye; akin to OFries. iu, io, D. u, G. euch, OHG. iu, dat., iuwih, acc., Icel. y[eth]r, dat. & acc., Goth. izwis; of uncertain origin. [root]189. Cf. Your.]

The pronoun of the second person, in the nominative, dative, and objective case, indicating the person or persons addressed. See the Note under Ye.

Ye go to Canterbury; God you speed. --Chaucer.

Good sir, I do in friendship counsel you To leave this place. --Shak.

In vain you tell your parting lover You wish fair winds may waft him over. --Prior.

Note: Though you is properly a plural, it is in all ordinary discourse used also in addressing a single person, yet properly always with a plural verb. ``Are you he that hangs the verses on the trees, wherein Rosalind is so admired ?'' --Shak. You and your are sometimes used indefinitely, like we, they, one, to express persons not specified. ``The looks at a distance like a new-plowed land; but as you come near it, you see nothing but a long heap of heavy, disjointed clods.'' --Addison. ``Your medalist and critic are much nearer related than the world imagine.'' --Addison. ``It is always pleasant to be forced to do what you wish to do, but what, until pressed, you dare not attempt.'' --Hook. You is often used reflexively for yourself of yourselves. ``Your highness shall repose you at the tower.'' --Shak.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Thou \Thou\, pron. [Sing.: nom. Thou; poss. Thyor Thine; obj. Thee. Pl.: nom. You; poss. Youror Yours; 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.

Art thou he that should come? --Matt. xi. 3.

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.

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

Source: Webster's Revised Unabridged Dictionary (1913)