The Collaborative International Dictionary of English v.0.48:

Communal \Com"mu*nal\ (? or ?), a. [Cf. F. communal.]
   1. Pertaining to a commune.
      [1913 Webster]

   2. resembling a commune[4] or the practises of a commune[4];
      as, communal living.

   Syn: collectivist.
        [PJC]

WordNet (r) 3.0 (2006):

communal
    adj 1: for or by a group rather than individuals; "dipping each
           his bread into a communal dish of stew"- Paul Roche; "a
           communal settlement in which all earnings and food were
           shared"; "a group effort"
    2: relating to a small administrative district or community;
       "communal elections in several European countries"

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "communal":
   associated, associational, civic, civil, coacting, coactive,
   coadjutant, coadjuvant, coalitional, coefficient, collaborative,
   collective, collectivist, collectivistic, collusive, combined,
   commensal, common, communalist, communalistic, communist,
   communistic, communitarian, commutual, concerted, concordant,
   concurrent, concurring, conjoint, conniving, cooperant,
   cooperating, cooperative, cosmopolitan, ecumenic, fellow, general,
   harmonious, harmonized, in common, international, joint, mutual,
   national, noncompetitive, organizational, popular, public,
   reciprocal, respective, sociable, social, socialistic, societal,
   society, state, supranational, symbiotic, synergetic, synergic,
   synergistic, two-way, uncompetitive