WordNet (r) 3.0 (2006):

multinational
    adj 1: involving or operating in several nations or
           nationalities; "multinational corporations";
           "transnational terrorist networks" [syn: multinational,
           transnational]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "multinational":
   amalgamated, ambiguous, ambivalent, amphibious, blended, combined,
   complex, composite, compound, compounded, conglomerate, dappled,
   eclectic, equivocal, fifty-fifty, half-and-half, heterogeneous,
   indiscriminate, intricate, ironic, jumbled, many-sided, medley,
   mingled, miscellaneous, mixed, motley, multifaceted, multiracial,
   patchy, pluralistic, promiscuous, scrambled, syncretic,
   thrown together, varied