From Longman Business Dictionary
multilateralmul·ti·lat·e·ral /ˌmʌltɪˈlætərəl◂/ adjectiveadjECONOMICS involving several different countriesa multilateral trade agreement
the World Bank and other multilateral development banks
→ compare bilateral, unilateral —multilaterally adverbadvConsultations took place both multilaterally and bilaterally.