Ontologies are widely considered to be the backbone of the Semantic Web. Its importance is being recognized in a multiplicity of research fields and application areas. Ontology building is crucial for the aforementioned issues. The main goal of this research is to investigate an effective methodology for collaborative ontology building. A trust-based consensus is proposed to support an efficient solution for conflicts among different viewpoints of participants in the collaborative ontology (CoO) building process. In every cycle of the iterative collaborative process, the ontology is refined and evolved by reaching a trust-based consensus among the participants’ viewpoints. The proposed method is applied for collaborative Vietnamese WordNet building. The result is significant in comparison with previous approaches.