Matching domain and top-level ontologies is an important task but still an open problem in the ontology matching field, particularly due to their different levels of abstraction. Beyond that, validating candidate alignments is crucial before exploiting them within ontology construction and integration processes involving such kinds of ontologies. This paper concerns the automatic validation of candidate alignments between top and domain ontologies, exploiting WordNet background knowledge. We apply our approach for validating alignments generated by a set of matching tools and discuss the results against manual validation. Our experiments are based on one domain ontology and three well-known top-level ontologies.