m- / wa- (kivumishi)

In Swahili, descriptive adjectives must agree with the nouns they modify. For humans and animals, you use the m- and wa- prefixes.

1. Consonant Stems
If an inflecting (Bantu) adjective starts with a consonant (like -zuri for "good" or -kubwa for "big"), simply attach m- for singular and wa- for plural:

• mtu mzuri (a good person)
• watu wazuri (good people)

2. Vowel Stems
If the adjective starts with a vowel, the singular prefix usually becomes mw- (m + a = mwa, m + e = mwe, m + i = mwi, m + o = mwo). Before -u, it can remain m- (e.g., mtoto mume (a male child)), but it often becomes mw- or mu- depending on the stem (e.g., mtu mwungwana or muungwana (a civilized person)). For the plural, the wa- prefix sometimes merges with the following vowel, but sometimes keeps both vowels (Concord Before Vowel Stems): wa + e = we, wa + o = wao, and wa + u = wau. While wa + a often becomes wa and wa + i often becomes we, these are not absolute rules. Some stems retain both vowels (e.g., watu waivu (jealous people), watu waaminifu (trustworthy people)).

• mtoto mweusi (a dark-skinned child)
• watoto weusi (dark-skinned children, from wa + eusi)

3. The Animacy Rule
A crucial rule in Swahili is the animacy rule. Descriptive adjectives modifying any animate nouns (animals, insects) must take Class 1/2 m-/wa- prefixes, regardless of the noun's actual class. For example, simba (lion) is a Class 9/10 noun that does not change form in the plural. Because of this, the adjective prefix is often the only word indicating plurality: you must say simba mkubwa (a big lion) and simba wakubwa (big lions), not simba kubwa. This applies across all classes containing animate beings. For example, with a Class 7/8 noun like kifaru (rhinoceros), you say kifaru mkubwa (a big rhinoceros) and vifaru wakubwa (big rhinoceroses).

Important Exceptions:

• Verbs are different: While Class 1 descriptive adjectives take m-, Class 1 verbs take the Class 1 Subject a- (e.g., mtu mzuri anasoma).
• Possessives for kinship terms: While descriptive adjectives for animate Class 9/10 nouns take Class 1/2 prefixes, Standard Swahili prescriptive rules state that possessives for human relationship terms (like rafiki, baba, mama) should take Class 9/10 prefixes (e.g., rafiki yangu). However, in everyday spoken Swahili, Class 1/2 prefixes (e.g., rafiki wangu) are extremely common.
• Loanwords: Loan Adjectives Without Concord (mostly from Arabic, like safi or ghali) never take any prefixes.

In wa + e → we there is vowel coalescence. In wa + o → wao and wa + u → wau, both vowel qualities remain side by side; those examples show concatenation rather than the same merger.