The Collaborative International Dictionary of English v.0.48:

Sty \Sty\ (st[imac]), n.; pl. Sties (st[imac]z). [Written also
   stigh.] [AS. stigu, fr. st[imac]gan to rise; originally,
   probably, a place into which animals climbed or went up.
   [root]164. See Sty, v. i., and cf. Steward.]
   1. A pen or inclosure for swine.
      [1913 Webster]

   2. A place of bestial debauchery.
      [1913 Webster]

            To roll with pleasure in a sensual sty. --Milton.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sty \Sty\, v. t. [imp. & p. p. Stied (st[imac]d); p. pr. & vb.
   n. Stying (st[imac]"[i^]ng).]
   To shut up in, or as in, a sty. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sty \Sty\, v. i. [OE. stien, sti[yogh]en, AS. st[imac]gan to
   rise; akin to D. stijgen, OS. & OHG. st[imac]gan, G. steigen,
   Icel. st[imac]ga, Sw. stiga, Dan. stige, Goth. steigan, L.
   vestigium footstep, Gr. ? to walk, to go, Skr. stigh to
   mount. Cf. Distich, Stair steps, Stirrup, Sty a boil,
   a pen for swine, Vestige.]
   To soar; to ascend; to mount. See Stirrup. [Obs.]
   [1913 Webster]

         With bolder wing shall dare aloft to sty,
         To the last praises of this Faery Queene. --Spenser.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sty \Sty\, n. [For older styan, styanye, understood as sty on
   eye, AS. st[imac]gend (sc. e['a]ge eye), properly, rising, or
   swelling (eye), p. p. of st[imac]gan to rise. See Sty, v.
   i.] (Med.)
   An inflamed swelling or boil on the edge of the eyelid.
   [Written also stye.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

sty
    n 1: an infection of the sebaceous gland of the eyelid [syn:
         sty, stye, hordeolum, eye infection]
    2: a pen for swine [syn: sty, pigsty, pigpen]