Somali is an agglutinative language, using many affixes and particles to determine and alter the meaning of words. As in other related Afroasiatic languages, Somali nouns are inflected for gender, number and case, while verbs are inflected for persons, number, tenses, and moods.

Affixes change according to a number of rules. The definite article is a suffix, with the basic form being -ki or -ka for masculine nouns and -ti or -ta for feminine nouns. The k or t is the actual article marker, although it can change depending on the preceding consonant, with the following vowel determined by the case of the noun. Articles do not change for singular or plural.

The basic form of a Somali noun is in absolutive case. In this case, the article maintains the vowel -a.

The subject of a sentence takes nominative case. In this case, the article takes the vowel -u. If the subject of the sentence includes multiple nouns, only the last takes the nominative ending for the article.

If there is no article, a tonal change signifies nominative case, although this is not represented in the orthography. Feminine nouns ending in a consonant take the suffix -i in nominative case without an article.

Genitive case is generally indicated through a tonal change. Some feminine nouns take an ending, -eed, -aad or -od, depending on the final consonant of the root word.

Vocative case is indicated either through a tonal change or with the suffixes -ow (m. sg.), -ohow (m. pl.), -eey/-aay/-ooy (f. sg.) or -yahay (f. pl.).

Gender is not marked in nouns without the definite article. The gender of nouns does not follow any particular rule and is not generally obvious.