Since Arabic has almost no cognates, students spend a lot of time memorizing new vocabulary. Once they realize the similarities and patterns on which Arabic words are built, this task becomes much easier. Arabic nouns are so manifold that they can be considered the largest group of words in the dictionary. If a word is not a verb or a preposition, it is most likely a noun. Adjectives are very similar to nouns, and quite often they can switch sides easily. A common definition of an Arabic noun is that it may take the definite article. It can also take the indefinite article, which in Arabic is marked by nunation (see section 1.3 below).