Arabic morphology is complex, partly because of its richness, and partly because of its complex morpho-syntactic agreement rules which depend on functional features not necessarily expressed in word forms.
challenging are broken plurals (which resemble singular nouns), nouns with irregular gender (masculine nouns that look feminine and feminine nouns that look masculine), and the semantic feature of rationality, which has no morphological realization (Smrž, 2007b;Alkuhlani and Habash, 2011).