Infinitive Class 15

Foundations

In Swahili, adding the prefix ku- to a verb root creates the infinitive (the dictionary form of the verb). It translates to both 'to [verb]' and the noun form '[verb]ing'.

How It Works

Welcome to Noun Class 15! In Swahili, the prefix ku- is attached to a verb root to create the infinitive. Before certain vowel-starting verb roots, ku- changes to kw- (for example, kwenda, kwisha, and kwanza).

A common misconception is that ku- is just the English word 'to'. In reality, it transforms the verb into a noun belonging to Class 15. This means a word like kusoma can mean both 'to read' and the act of 'reading'. Class 15 is an unpaired class, meaning these nouns have no plural form.

Because it is a noun, it can act as the subject of your sentence. When it does, it dictates the grammar of the rest of the sentence, requiring specific Class 15 agreement markers (like the subject prefix ku-, the adjective prefix ku-, kw- for possessives, and the associative marker kwa for 'of', as in kusoma kwa mwanafunzi). Its demonstratives are huku (this), huko (that), and kule (that over there), and its object infix is -ku-. Be aware that this Class 15 object infix looks identical to the Second-Person Object -ku- ('you'), which is a common source of confusion for learners!

Key Concepts to Explore:

Note: Be careful not to confuse this noun class with the General Place ku- (Class 17), which looks identical but refers to locations!

Examples (4)

  1. Kusoma ni kuzuri.

    Reading is good.

    Word by Word: To-read is good.

    This shows the infinitive acting as a noun subject, forcing the adjective (-zuri) to take the Class 15 agreement prefix (ku-).

  2. Ninapenda kupika.

    I like to cook. / I like cooking.

    Word by Word: I-present-like to-cook.

    Here, the Class 15 noun acts as the object of another verb.

  3. Kuimba kwake kunapendeza.

    His/her singing is pleasing.

    Word by Word: To-sing his/her it-present-please.

    This demonstrates full Class 15 agreement across the sentence: the possessive takes kw- (kwake) and the verb takes the subject marker ku- (kunapendeza).

  4. Ninakula.

    I am eating.

    Word by Word: I-present-to-eat.

    For short (monosyllabic) verbs like -la (eat), the ku- prefix is retained even when conjugated to maintain the word's rhythm.

Common Mistakes

  • Defaulting to Class 9 agreement instead of Class 15.

    Kusoma ni nzuri.
    Kusoma ni kuzuri.

    Because English gerunds ('reading') don't have noun classes, learners often forget to use Class 15 agreement, defaulting to the common Class 9 'n-' prefix for adjectives. You must use the Class 15 'ku-' prefix.

  • Dropping the ku- prefix on short (monosyllabic) verbs.

    Ninala.
    Ninakula.

    Short verbs like -la (eat) or -ja (come) must keep the ku- prefix in certain tenses to maintain the rhythm of the word (penultimate stress). They are completely regular, but the prefix is required for pronunciation.

How It Connects

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Infinitive Class 15Foundations

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Words in This Pattern

ku-