The Collaborative International Dictionary of English v.0.48:

Eleven \E*lev"en\ ([-e]*l[e^]v"'n), a. [OE. enleven, AS.
   endleofan, endlufon, for nleofan; akin to LG. eleve, ["o]lwe,
   ["o]lwen, D. elf, G. elf, eilf, OHG. einlif, Icel. ellifu,
   Sw. elfva, Dan. elleve, Goth. ainlif, cf. Lith. v["e]nolika;
   and fr. the root of E. one + (prob.) a root signifying "to be
   left over, remain," appearing in E. loan, or perh. in leave,
   v. t., life. See One, and cf. Twelve.]
   Ten and one added; as, eleven men.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Eleven \E*lev"en\, n.
   1. The sum of ten and one; eleven units or objects.
      [1913 Webster]

   2. A symbol representing eleven units, as 11 or xi.
      [1913 Webster]

   3. (Cricket & American Football) The eleven men selected to
      play on one side in a match, as the representatives of a
      club or a locality; as, the all-England eleven.
      [1913 Webster]

WordNet (r) 3.0 (2006):

eleven
    adj 1: being one more than ten [syn: eleven, 11, xi]
    n 1: the cardinal number that is the sum of ten and one [syn:
         eleven, 11, XI]
    2: a team that plays football [syn: football team, eleven]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "eleven":
   L, Sexagesima, boxcar, boxcars, cast, company, complement, crew,
   dozen, duodecimo, eight, eighty, fifteen, fifty, first string,
   first team, five, five and twenty, fortnight, forty,
   four and twenty, fourscore, fourscore and ten, fourteen,
   half a hundred, long dozen, nine, ninety, nonagenarian,
   octogenarian, platoon, quindecennial, quindecim, quindecima,
   quindene, reserves, rowing crew, score, second string, second team,
   septuagenarian, seventy, sexagenarian, sexagenary,
   sexagesimo-quarto, sixteen, sixteenmo, sixty, sixty-four,
   sixty-fourmo, squad, string, team, teens, third string, thirteen,
   thirty-two, thirty-twomo, threescore, threescore and ten, twelve,
   twelvemo, twenty, twenty-five, twenty-four, twenty-fourmo,
   two dozen, two weeks, twoscore, varsity