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]