This book is a resource for being familiar with ontology mapping, especially bilingual ontology mapping which is a new research area in ontology engineering. By the help of bilingual ontology mapping, new ontologies, especially lexical ontologies can be constructed for a certain language getting help from existing ontologies of other languages. WordNet has a remarkable role in this area. It is a powerful semantic and syntactic resource which is widely used in natural language processing applications. PenMap Methodology is suggested in this book to map two lexical ontologies in two different languages.