This paper aims to systematically analyze the formal marking of numbers on common nouns and adjectives of Sidaama, a Highland East Cushitic (HEC hereafter) language spoken in Ethiopia. There are three formal categories of number in Sidaama: basic form, singulative, and plurative. The basic form is a form of a noun that is not marked for number; a singulative denotes a single referent, and a plurative marks multiple referents. The singulative of nouns is usually marked either by -ʧ-o ~ -ʧʧ-o. There are also a few nouns that contain the formatives -ʃ-o, -ʧ-o, and -k-o as markers of the singulative. Such forms arose from the merging of the final consonant of the nominal root with the initial -ʧ of the singulative. Unlike nouns, singulative is marked only on a handful of adjectives. Five types of nominals and six types of adjectival pluratives are identified. All of them are suffixal, and two of them involve the copying of a root-final consonant. Sidaama has inherently singular nouns that usually denote humans and higher animals. In such nouns, their basic form marks a single referent. The language also contains inherently plural nouns that refer to a collective of entities or a group. Few nouns are transnumeral; in their basic form, they can refer to either a single entity or plural entities.
Anbessa Teferra (Fri,) studied this question.