What distinguishes morphologically rich languages (MRL), like Arabic, from other languages is that their words include more morphemes (such as prefixes and suffixes) representing a number of morphological features, e.g., gender, number, person, mood, as well as attachable clitics.
table 1 shows the set of 16 Arabic morphological features we model MRLs tend to have more fully inflected words (types) than their poor counterparts.