Arabic is a Semitic language spoken by millions of people in more than 20 different countries. However, not much work has been done in the field of online dictionaries or lexical resources. WordNet is an example of a lexical resource that has not been yet developed for Arabic. WordNet, a lexical database developed at Princeton University, has seen life 15 years ago. Ever since then, it has proved to be widely successful and extremely necessary for today's demands for processing natural languages. Accordingly, the motivation of developing an Arabic WordNet became strong. In this paper we tackle some of the challenges inherent to constructing an Arabic lexical reference system. The paper goes through some solutions adopted in existing WordNets and presents justifications for adopting the Arabic WordNet's (AWN) philosophy. We address the nominal part of Arabic WordNet as the first step towards the construction of a comprehensive Arabic WordNet. The nominal part means nouns as a part of speech.