The Collaborative International Dictionary of English v.0.48:

Enlist \En*list"\, v. t. [imp. & p. p. Enlisted; p. pr. & vb.
   n. Enlisting.]
   1. To enter on a list; to enroll; to register.
      [1913 Webster]

   2. To engage for military or naval service, the name being
      entered on a list or register; as, to enlist men.
      [1913 Webster]

   3. To secure the support and aid of; to employ in advancing
      interest; as, to enlist persons in the cause of truth, or
      in a charitable enterprise.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Enlist \En*list"\, v. i.
   1. To enroll and bind one's self for military or naval
      service; as, he enlisted in the regular army; the men
      enlisted for the war.
      [1913 Webster]

   2. To enter heartily into a cause, as if enrolled.
      [1913 Webster]

WordNet (r) 3.0 (2006):

enlist
    v 1: join the military
    2: hire for work or assistance; "engage aid, help, services, or
       support" [syn: engage, enlist]
    3: engage somebody to enter the army [syn: enlist, draft,
       muster in] [ant: discharge, muster out]

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "enlist":
   affiliate, affiliate with, alternate, associate, bring, call up,
   carry, combine, come into, commandeer, conscript, cover, creep in,
   decide, detach, detach for service, determine, dispose, do a hitch,
   do a stint, do a tour, do time, draft, employ, engage, enroll,
   enter, fill in for, gather, get, get into, get to do, go into,
   have a go, have tenure, hire, hold office, impress, inaugurate,
   incline, induce, induct, influence, initiate, install, instate,
   interest in, invest, join, join up, keep a watch, lead,
   league with, levy, list, lure, make available, mobilize, muster,
   muster in, obtain, ordain, organize, press, procure, prompt, raise,
   re-up, recruit, reenlist, register, relieve, retain, secure,
   serve time, sign on, sign up, sneak in, spell, spell off, summon,
   sway, take out membership, take turns, take up membership,
   team up with, team with, tempt, time off, volunteer