-vyo- (ngeli ya 8)

The relative marker -vyo- has two main jobs in Swahili:

1. Class 8 Noun Modifier ("which/that")
When referring back to a Class 8 noun (like viti or vitabu), -vyo- acts as the relative pronoun. When the Class 8 noun is the subject of the sentence, the subject prefix is vi- alongside the relative infix -vyo-. For example, vitabu vinavyoanguka (the books which are falling). When the relative acts as the object of the sentence, standard Swahili prefers including the Class 8 Object -vi- right before the verb root. For example, vitabu ninavyovisoma (the books which I am reading).

2. Adverbial Relative of Manner ("how/as")
Even without a Class 8 noun, -vyo- is heavily used to mean "how", "the way that", or "as". It is very commonly paired with the words jinsi or namna to express "how" (e.g., jinsi unavyoimba = "how you sing"). For example, kama unavyojua means "as you know".

How to Attach -vyo-

• Infixed in the verb: It sits between the tense marker and the verb root. This infix position is limited to four tenses: -na- present, -li- past, -ta- future (which changes to -taka-), and the negative -si-. Note that when using the negative -si-, the standard initial negative prefixes (like ha- or hu-) are dropped, the subject prefix reverts to its affirmative form, and the final vowel of the verb stem reverts from the negative -i back to the affirmative -a (e.g., hasomi becomes asivyosoma). Also, monosyllabic verbs retain their ku- with all infixed relative tenses (e.g., ninavyokula, nilivyokula, nisivyokula) to maintain stress.
• As a suffix (Tenseless Relative): It can be attached directly to the final vowel of the verb stem for a general or habitual meaning (Subject + [Object] + Verb Stem + vyo). For example, kama ujuavyo (as you know) or ufikirivyo (as you think). Monosyllabic verbs drop their ku- here (e.g., ulavyo). This uses the Tenseless Relative suffix -vyo.
• With amba-: While you must use the independent word ambavyo for tenses that cannot take an infix (like the -me- perfect), it is also perfectly grammatical and very common to use it with any other tense (e.g., vitabu ambavyo ninavisoma is just as valid as vitabu ninavyovisoma). Additionally, because the infixed -si- only creates a general or tenseless negative, you must use amba- to express specific negative tenses (e.g., vitabu ambavyo sikusoma for the past negative).
• With copulas/prepositions: It attaches to ndi- for emphasis (ndivyo = "that is how") and its negative counterpart sivyo ("that is not how" or "not so"). It also attaches to na (navyo = "with them", or to express possession like "have them", e.g., ninavyo = "I have them").