The Collaborative International Dictionary of English v.0.48:

Somebody \Some"bod*y\ (s[u^]m"b[o^]d*[y^]), n.
   1. A person unknown or uncertain; a person indeterminate;
      some person.
      [1913 Webster]

            Jesus said, Somebody hath touched me. --Luke viii.
                                                  46.
      [1913 Webster]

            We must draw in somebody that may stand
            'Twixt us and danger.                 --Denham.
      [1913 Webster]

   2. A person of consideration or importance.
      [1913 Webster]

            Before these days rose up Theudas, boasting himself
            to be somebody.                       --Acts v. 36.
      [1913 Webster]

WordNet (r) 3.0 (2006):

somebody
    n 1: a human being; "there was too much for one person to do"
         [syn: person, individual, someone, somebody,
         mortal, soul]

Moby Thesaurus II by Grady Ward, 1.0:

106 Moby Thesaurus words for "somebody":
   Adamite, Establishment, VIP, baron, being, big cheese, big gun,
   big man, big name, big noise, big wheel, big-timer, bigwig, body,
   brass, brass hat, cat, celebrity, chap, character, constellation,
   creature, customer, cynosure, dignitary, dignity, duck, earthling,
   elder, father, fellow, figure, folk hero, galaxy, great man,
   groundling, guy, hand, head, heavyweight, hero, heroine,
   high-muck-a-muck, homo, hotshot, human, human being, idol,
   immortal, important person, individual, interests, joker, leader,
   life, lion, living soul, lords of creation, luminaries, luminary,
   magnate, man, man of mark, master spirit, mogul, mortal, nabob,
   name, nose, notability, notable, one, panjandrum, party, person,
   person of note, person of renown, personage, personality,
   pillar of society, pleiad, pop hero, popular hero, popular idol,
   power, power elite, public figure, ruling circle, sachem, single,
   social lion, someone, something, soul, star, superstar, tellurian,
   terran, the great, the top, top brass, top people, tycoon,
   very important person, worldling, worthy