-o-

The relative marker occupies a specific slot in the Swahili verb template: Subject – Tense – Relative – Object – Verb Root – Final Vowel.

Forming the Marker:
The relative marker is formed using the '-o- of reference' (the class agreement prefix + o), with the exception of Class 1 which uses -ye-. Note the vowel mergers: wa + o = o (Class 2), u + o = o (Classes 3/11/14), i + o = yo (Classes 4/9), li + o = lo (Class 5), ya + o = yo (Class 6), ki + o = cho (Class 7), vi + o = vyo (Class 8), and zi + o = zo (Class 10).

Tense Restrictions:
This pattern is exclusively used with three specific affirmative tenses:

• Present: -na-
• Past: -li-
• Future: -taka- (Note: You must use the expanded future relative -taka- instead of the usual -ta-)

Negative Relatives:
To form a negative relative, the negative marker -si- replaces the tense marker entirely, resulting in a tenseless verb whose time frame depends on context. Note that the final vowel of the verb remains -a (e.g., asiyesoma) and does not change to -i as it does in the standard present negative. To specify a negative past or future relative, you must use the amba- construction with standard negative verbs (e.g., ambaye hakusoma, ambaye hatasoma).

Tenseless Relatives:
In addition to the tensed forms, there is an affirmative tenseless relative (the general relative) where the relative marker is attached as a suffix to the verb stem (after the final vowel) (e.g., asomaye - he who reads).

Monosyllabic Verbs:
When using verbs with single-syllable roots (like kula, kuja, kunywa), the infinitive ku- is retained in tensed relative forms (e.g., anayekula - he who is eating). However, in the tenseless suffix relative, the ku- is dropped (e.g., alaye - he who eats). For more details, see Ku- Retention in Short Verbs.

Locative and Manner Relatives:
The relative markers are also used to express time, place, and manner. The locative relatives -po- (when/where specific), -ko- (where general), and -mo- (where inside) are essential for expressing 'when' and 'where'. The manner relative -vyo- is used to express 'how' or 'the way that'.

Alternatives:
If you need to express a relative clause with other tenses (like the perfect -me-, the negative perfect -ja-, or conditional -nge-), you must use amba- relatives. For example, to say 'who has read' you use ambaye amesoma, and for 'who has not yet read' you use ambaye hajasoma. While amba- is required for these specific tenses, it is also perfectly grammatical and very common to use it with any tense, including -na-, -li-, and -ta-.

Subject vs. Object Relatives:
When the head noun is the subject performing the action, the relative marker agrees with the subject prefix. When relativizing an object, the relative marker must agree with the noun class of the object, not the subject. Additionally, you must include the object marker in the verb alongside the relative marker. In Standard Swahili, this object concord is strictly required when relativizing an object, regardless of whether it is animate or inanimate (e.g., kitabu nilichokisoma).

Note: While commonly called an 'infix' in textbooks, linguistically it is a prefix in the verbal chain.

Formal Object-Relative Model:
The examples here use an object marker for both animate and inanimate object relatives. You may encounter variation in speech and descriptions of particular relative constructions, but preserving the object marker is a clear model for careful written Swahili.