The Collaborative International Dictionary of English v.0.48:

Eight \Eight\ ([=a]t), n.
   1. The number greater by a unit than seven; eight units or
      objects.
      [1913 Webster]

   2. A symbol representing eight units, as 8 or viii.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Eight \Eight\ ([=a]t), n. [See Ait.]
   An island in a river; an ait. [Obs.] "Osiers on their
   eights." --Evelyn.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Eight \Eight\ ([=a]t), a. [AS. eahta; akin to OS. ahto, OFries.
   achta, D. & G. acht, OHG. ahto, Icel. [=a]tta, Sw. [*a]tta,
   Dan. otte, Goth. ahtau, Lith. aszt[*u]ni, Ir. & Gael. ochd,
   W. wyth, Armor. eich, eiz, L. octo, Gr. 'oktw`, Skr.
   ash[.t]an. [root]306. Cf. Octave.]
   Seven and one; as, eight years.
   [1913 Webster]

WordNet (r) 3.0 (2006):

eight
    adj 1: being one more than seven [syn: eight, 8, viii]
    n 1: the cardinal number that is the sum of seven and one [syn:
         eight, 8, VIII, eighter, eighter from Decatur,
         octad, ogdoad, octonary, octet]
    2: a group of United States painters founded in 1907 and noted
       for their realistic depictions of sordid aspects of city life
       [syn: Ashcan School, Eight]
    3: one of four playing cards in a deck with eight pips on the
       face [syn: eight-spot, eight]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "eight":
   Octateuch, cast, company, complement, crew, eighter from Decatur,
   eleven, first string, first team, five, nine, octad, octagon,
   octahedron, octameter, octastyle, octave, octavo, octet, octonary,
   octosyllable, ogdoad, platoon, reserves, rowing crew,
   second string, second team, squad, string, team, third string,
   utas, varsity