Like most other Bantu languages, Kinyarwanda is tonal and also agglutinative: most words are formed as a series of morphemes, including a prefix, a stem, and sometimes a preprefix. Nouns are divided into sixteen classes, covering both singular and plural nouns. Some of the classes are used exclusively for particular types of noun; for example classes 1 and 2 are for nouns related to people, singular and plural respectively, classes 7, 8 and 11 refer to big versions of nouns in other classes, and class 14 is for abstract nouns. Adjectives applied to nouns generally take a prefix matching the prefix of the noun. For example, the word "abantu" (people) is a class 2 noun with preprefix "a-" and prefix "ba-"; when applying the adjective "-biri" (two) to that noun, it takes the class 2 prefix "ba-", so "two people" translates as "abantu babiri"; "ibintu" (things) is a class 4 noun with prefix "bi-", thus "two things" translates as "ibintu bibiri".