Infinitives and Verbal Nouns (Ku-) in Swahili

In Brief

Add ku- to a verb stem to form the Swahili infinitive: kusoma can mean “to read” or “reading,” depending on its role. The same form can complete another verb, follow expressions such as kabla ya “before,” or act as a class 15 noun: Kusoma kunasaidia means “Reading helps.”

Overview

An infinitive is the basic, non-tensed form of a verb—the form often translated into English with “to,” as in “to read.” In Swahili, it normally begins with ku-: kusoma “to read,” kufanya “to do,” and kusafiri “to travel.” Unlike English, Swahili does not normally need separate forms corresponding to “to read” and the verbal use of “reading.” The context supplies the most natural English translation.

The Swahili infinitive is also a verbal noun: a verb form that names an activity and can occupy places where a noun would occur. It can be the subject (what a sentence is about), as in Kuogelea kunafurahisha “Swimming is enjoyable,” or the object/complement (what completes the meaning of another verb), as in Ninapenda kuogelea “I like swimming.” Because these forms are treated as nouns of class 15, they can control ku- agreement on other words.

At B1, this pattern lets you connect familiar present-tense verbs to longer, more natural statements. You can discuss preferences and abilities, place one action before or after another, and explain why someone goes or comes somewhere. English is a useful guide to the meaning, but not to the exact structure: English alternates among “to do,” “doing,” and clauses such as “that I do,” while Swahili often uses one ku- form.

How It Works

Forming the infinitive

The basic pattern is:

ku- + verb stem

Stem	Infinitive	Core meaning
-soma	kusoma	to read; to study
-fanya	kufanya	to do; to make
-lala	kulala	to sleep
-andika	kuandika	to write
-safiri	kusafiri	to travel
-zungumza	kuzungumza	to speak; to converse

The final -a belongs to most ordinary Bantu verb stems; do not add another ending after it. Loan verbs may end differently, but still take ku-: kujibu “to answer,” kusafiri “to travel,” and kusamehe “to forgive.”

A few frequent forms deserve to be learned whole:

Infinitive	Meaning	What to notice
kula	to eat	short stem -la
kunywa	to drink	stem begins with a consonant cluster
kuja	to come	short stem -ja
kwenda	to go	kuenda contracts to common kwenda
kuwa	to be; to become	frequent as both a main verb and an auxiliary

With short, one-syllable stems such as -la and -ja, ku- is retained in contexts where longer verbs may show only their stem inside a conjugated verb. Compare ninakula “I am eating” and ninakuja “I am coming” with ninasoma “I am reading.” This retention inside tense forms is a broader verb-formation issue; in the infinitive itself, all these forms simply begin with ku-.

“To do” and “doing” use the same form

English form does not determine the Swahili form. Choose the English wording that sounds natural after understanding the Swahili sentence:

Function	Swahili	Natural English
complement of another verb	Nataka kusoma.	I want to read.
named activity	Kusoma ni muhimu.	Reading is important.
after a time expression	Baada ya kusoma...	After reading...
purpose after movement	Alikuja kusoma.	He/She came to study.

This is why translating each English “-ing” form mechanically is unreliable. In “I am reading,” reading is part of an ongoing present tense, so Swahili uses ninasoma, not an independent infinitive. In “Reading is useful,” reading names the activity, so kusoma is appropriate.

As the complement of another verb

Many verbs are followed directly by a ku- infinitive. The first verb carries the subject and tense; the infinitive names the second action.

subject + tense-bearing verb + ku-infinitive

• Ninataka kuondoka. — I want to leave.
• Anaweza kuendesha gari. — He/She can drive.
• Tulianza kujifunza Kiswahili. — We began to learn Swahili.
• Wameacha kuvuta sigara. — They have stopped smoking.
• Napenda kupika. — I like cooking/to cook.

Do not conjugate both verbs merely because English has two verbal ideas. In Ninaweza kuogelea, only ninaweza carries the subject prefix ni- and present marker -na-. The following kuogelea remains an infinitive.

As a class 15 noun

Swahili groups nouns into classes that control agreement—matching prefixes on verbs, adjectives, demonstratives, and some other words. An infinitive used as an activity noun belongs to class 15 and normally triggers ku- agreement.

Role	Agreement pattern	Example
subject of a verb	ku- subject agreement	Kutembea kunasaidia. “Walking helps.”
with an adjective after ni	class 15 ku-	Kusoma ni kuzuri. “Reading is good.”
with a demonstrative	class 15 form	Kuimba huku kunafurahisha. “This singing is enjoyable.”

In Kusafiri kunachosha, the first ku- forms the infinitive kusafiri; the second ku- in kunachosha agrees with that whole activity as the subject. It is followed by present -na- and the verb -chosha “tire”: ku-na-chosha.

When ni links the activity to an adjective, class agreement can still appear on the adjective: Kusoma ni kuzuri “Reading is good.” In everyday communication, speakers may also choose a noun or clause that changes the agreement pattern, so learn the clear class 15 model before analysing variation.

After prepositions and linking expressions

Many time and sequence expressions contain ya, followed by the infinitive:

• kabla ya kulala — before sleeping / before going to bed
• baada ya kula — after eating
• wakati wa kusoma — time for studying
• badala ya kulalamika — instead of complaining

Here ya or wa is part of the linking expression. English may use a bare “before + -ing,” but Swahili normally keeps the linker: kabla ya kuondoka, not kabla kuondoka.

An infinitive can also follow an ordinary prepositional relationship where an action is treated as a noun: kwa kufanya hivyo “by doing so” or “through doing that.” The precise English preposition may change with context.

Expressing purpose

After movement verbs, a following infinitive commonly states the purpose of the movement:

• Nimekuja kukuona. — I have come to see you.
• Alienda sokoni kununua matunda. — He/She went to the market to buy fruit.
• Tulirudi nyumbani kupumzika. — We returned home to rest.

The form kukuona contains two different ku elements: infinitive ku- plus the second-person-singular object marker -ku- “you,” followed by -ona “see.” Its structure is ku-ku-ona. Repeated syllables are not necessarily a mistake.

Not every English purpose clause should become a bare infinitive. When the purpose has a separately stated subject, or when the speaker presents a desired outcome rather than simply the mover’s own action, Swahili often uses ili followed by an appropriate finite or subjunctive form: Ninasema polepole ili watoto waelewe “I speak slowly so that the children understand.”

Examples in Context

Swahili	English	Note
Kusoma ni kuzuri.	Reading is good.	Infinitive as a class 15 activity noun
Ninapenda kusafiri.	I like travelling / to travel.	Complement of -penda
Kabla ya kulala, soma kitabu.	Before going to sleep, read a book.	kabla ya + infinitive
Kufanya kazi kunachosha.	Working is tiring.	ku- subject agreement on kunachosha
Kufanya kazi kunachekesha.	Working is amusing.	-chekesha means “make laugh/amuse,” not “tire”
Ninaweza kuzungumza Kiswahili kidogo.	I can speak a little Swahili.	Modal verb + infinitive
Tunataka kuanza sasa.	We want to begin now.	Only the first verb carries tense and subject marking
Baada ya kula, waliondoka.	After eating, they left.	Completed action after baada ya
Badala ya kulalamika, tafuta suluhisho.	Instead of complaining, look for a solution.	Infinitive names the alternative action
Alikwenda dukani kununua maziwa.	He/She went to the shop to buy milk.	Purpose after movement
Nimekuja kukuona.	I have come to see you.	Infinitive ku- plus object marker -ku-
Kuamka mapema kunahitaji mazoea.	Waking up early requires practice.	The whole phrase is the subject
Waliacha kuvuta sigara.	They stopped smoking.	Infinitive after -acha
Kwa kufanya hivyo, utaokoa muda.	By doing that, you will save time.	Action treated as a noun after kwa

The supplied sentence Kufanya kazi kunachekesha is grammatically well formed, but its accurate meaning is “Working is amusing” or “Working makes one laugh.” For “Working is tiring,” use Kufanya kazi kunachosha, because -chosha means “to tire” while -chekesha means “to make laugh.”

Common Mistakes

Dropping ku- after another verb

• Wrong: Ninataka soma.
• Right: Ninataka kusoma.
• Why: After -taka “want,” the second action is normally a ku- infinitive. English “want to read” also has a marker, but Swahili attaches its marker directly to the verb.

Conjugating both verbs

• Wrong: Ninaweza ninaogelea.
• Right: Ninaweza kuogelea.
• Why: In this construction, ninaweza carries the subject and tense. The action enabled by it stays in the infinitive.

Using the infinitive for an ongoing present action

• Wrong: Mimi kusoma sasa.
• Right: Ninasoma sasa.
• Why: “I am reading now” needs a finite verb—a verb marked for its subject and tense. Kusoma names “to read/reading” but does not by itself mean “I am reading.”

Forgetting the linker after kabla or baada

• Wrong: Kabla kulala, zima taa.
• Right: Kabla ya kulala, zima taa.
• Why: Standard kabla ya “before” and baada ya “after” include ya before the action noun.

Using the wrong agreement for an infinitive subject

• Wrong: Kusafiri inachosha.
• Right: Kusafiri kunachosha.
• Why: The infinitive is a class 15 noun here, so the agreeing verb begins with ku-, not class 9 i-.

Confusing -chekesha and -chosha

• Wrong for “Working is tiring”: Kufanya kazi kunachekesha.
• Right: Kufanya kazi kunachosha.
• Why: -chekesha is “make laugh/amuse”; -chosha is “tire.” The grammar is correct in both sentences, but the meanings differ.

Usage Notes

The English translation is flexible

After verbs such as “like,” English may allow both an infinitive and an -ing form: “I like to travel” and “I like travelling.” Swahili Ninapenda kusafiri does not encode that English distinction. Translate for natural meaning rather than assigning ku- permanently to English “to.”

Conversely, not every English -ing word is a Swahili infinitive. An ongoing event uses tense marking (anapika, “he/she is cooking”), and an English noun ending in -ing may have a more established Swahili noun depending on context. Use the infinitive when you are presenting the activity as an action or completing a verb that selects it.

Kwenda and kuenda

The sequence ku + enda commonly contracts to kwenda, the usual form learners encounter for “to go.” Kuenda also occurs, but kwenda is the safest general form to produce. Similar sound adjustments can happen where prefixes meet vowel-initial stems; they do not change the grammatical function.

The agent may be understood from context

In Kabla ya kuondoka, alifunga mlango “Before leaving, he/she locked the door,” listeners normally understand the person leaving to be the subject of the main clause. If two different people are involved, a fuller clause is clearer: Kabla mtoto hajaondoka, mama alifunga mlango “Before the child left, the mother closed the door.” Avoid relying on an infinitive when its understood doer could be ambiguous.

Purpose depends on clause structure

A bare infinitive after “go” or “come” is especially natural when the same person performs both actions: Alienda kusoma “He/She went to study.” Use ili when you need to introduce a different subject or emphasize an intended result: Alienda mjini ili watoto wabaki nyumbani “He/She went to town so that the children would remain at home.” This contrast involves the subjunctive and is worth learning as a separate topic.

Beyond the Basics / Advanced Use

Infinitives can contain object markers

The infinitive remains verbal inside: it can take an object noun or an object marker. Compare:

• kusoma kitabu — to read a book
• kukisoma — to read it (the class 7 object, such as kitabu)
• kuwapigia simu — to phone them
• kukuona — to see you

In kukisoma, the first ku- marks the infinitive, -ki- refers to a class 7 object, and -soma is the stem. In kukuona, identical-looking syllables have different jobs. Learning to segment the form from left to right prevents confusion.

Negating an infinitive

The negative infinitive commonly uses kuto- before the verb stem:

• kutofika kwa wakati — not arriving on time
• Kutosoma kunaleta matatizo. — Not studying causes problems.
• Aliamua kutokwenda. — He/She decided not to go.

Before a vowel-initial stem, ordinary sound combination may appear, as in kutokwenda. Negative infinitives are useful in formal explanation and abstract discussion; in conversation, speakers may sometimes prefer a finite negative clause if it is clearer.

A possessive can identify the doer

Because the infinitive behaves as a noun, a possessive expression can specify whose action is meant:

• kuja kwako — your coming / for you to come
• kuondoka kwake — his/her leaving
• Kuchelewa kwao kulitushangaza. — Their lateness surprised us.

Notice class 15 possessive agreement kwa-: kwangu, kwako, kwake, kwetu, kwenu, kwao. Context is essential because the same forms occur in other constructions with kwa.

Infinitive noun versus lexical noun

An infinitive focuses on the activity itself: kujenga “building/to build.” Swahili may also have a related established noun with a more specialized meaning, profession, result, or process. These are not always interchangeable. When you mean “the act of doing X,” the infinitive is productive and transparent; when naming a recognized object, occupation, or technical concept, learn the ordinary noun used by speakers.

Practice Tips

1. Build three versions from one verb. For each new stem, make a present-tense sentence, a complement, and an activity subject: Ninasoma “I am reading,” Nataka kusoma “I want to read,” Kusoma kunasaidia “Reading helps.” This trains you to distinguish a finite verb from an infinitive.
2. Mark the jobs of repeated prefixes. Break forms into meaningful pieces: ku-ku-ona (infinitive + “you” object + see) and ku-na-chosha (class 15 subject agreement + present + tire). Say each meaning aloud instead of memorizing the letter sequence alone.
3. Practise everyday connectors. Complete short prompts with real plans: kabla ya..., baada ya..., badala ya..., and nimekuja.... Check that ya remains after kabla and baada, and use a bare purpose infinitive only when the context is clear.

Related Concepts

• Prerequisite: Present Tense (-na-) — helps you distinguish a tense-marked verb such as ninasoma from the infinitive kusoma.
• Next step: Noun-class agreement — explains why an activity used as a class 15 subject triggers ku- in forms such as kunasaidia.
• Next step: Modal and complement verbs — expands patterns such as ninaweza kufanya, ninataka kwenda, and nimeanza kujifunza.
• Next step: Purpose clauses and the subjunctive — develops the contrast between a same-subject infinitive and ili with a fuller clause.