Copular si means “is not” or “are not” in present nonverbal predicates: Asha si daktari “Asha is not a doctor,” vitabu hivi si vipya “these books are not new.” It is a separate, invariable word. It does not change for person, number, or noun class.
This si must be distinguished from the first-person negative subject prefix si- inside a verb: sisomi “I do not read.” It also differs from negative possession sina “I do not have.” English uses forms of “be” across all three environments, but Swahili selects the construction according to the predicate.
Identity and classification
Affirmative ni identifies or classifies; negative si rejects that identity or category.
| Subject | Affirmative | Negative |
|---|---|---|
| mimi | Mimi ni mwalimu. | Mimi si mwalimu. |
| wewe | Wewe ni mgeni. | Wewe si mgeni. |
| yeye | Yeye ni daktari. | Yeye si daktari. |
| sisi | Sisi ni majirani. | Sisi si majirani. |
| ninyi | Ninyi ni washiriki. | Ninyi si washiriki. |
| wao | Wao ni walinzi. | Wao si walinzi. |
The copula itself never becomes hasi, hawasi, or another agreeing form. Number appears in the subject and predicate noun: mwalimu/waalimu, mgeni/wageni. For the affirmative structure, see ni identification.
Mimi si mwenyeji wa Mombasa, lakini nimeishi hapa kwa miaka mingi.
I am not a native of Mombasa, but I have lived here for many years.
Hawa si watalii; wamekuja kuhudhuria mkutano wa afya.
These people are not tourists; they have come to attend a health conference.
Kifaa hiki si simu; ni kinasa sauti cha mkutano.
This device is not a phone; it is a meeting recorder.
Adjective and ownership predicates
Copular si can negate a property expressed by an adjective or an ownership expression. The adjective or possessive retains the concord required by its noun.
Chumba cha mbele si kikubwa, lakini kina mwanga wa kutosha.
The front room is not large, but it has enough light.
Class 7 chumba selects adjective kikubwa. Negative si contributes no class marking.
Maembe haya si mabivu; tuyape siku mbili zaidi.
These mangoes are not ripe; let us give them two more days.
Class 6 maembe selects mabivu. In ordinary speech some present property predicates may occur without affirmative ni, but negative si overtly marks the rejected property. The affirmative environments for zero and overt copulas are explained on the zero-copula page.
Mwavuli huu si wangu; wangu una mpini wa mbao.
This umbrella is not mine; mine has a wooden handle.
Possessive predicate wangu agrees with class 3 mwavuli. This means the umbrella does not belong to me. It is different from sina mwavuli “I do not have an umbrella,” which uses the negative-possession paradigm.
Viti vilivyo karibu na dirisha si vyetu.
The chairs near the window are not ours.
Class 8 possessive vyetu agrees with viti; si remains unchanged.
Rejecting a focused alternative
Copular si can negate a focused noun, time, place, or other constituent: “not X (but perhaps Y).” This is especially common in corrections and contrasts.
Si Amina aliyepiga simu; alikuwa dada yake.
It was not Amina who called; it was her sister.
Mkutano si leo, ni kesho saa nne asubuhi.
The meeting is not today; it is tomorrow at ten in the morning.
Tuliahidi kukutana mjini, si kituoni.
We agreed to meet in town, not at the station.
This use does not negate the tense morphology of tuliahidi. It contrasts the locative constituent kituoni. English places “not” before many constituent types; Swahili si can similarly establish a copular contrast, especially when an alternative is explicit.
Focused si is neutral in (informal) corrections and (formal) argument. In formal prose, make the contrasted alternatives explicit when the scope could otherwise be unclear. The advanced scope and contrast page develops those ambiguities.
si, siyo, and verbal si-
Standalone siyo can answer or contradict a proposition with “it is not / no, it is not,” and it can be more emphatic or anaphoric than simple predicative si. The full contrast belongs to ndiyo and siyo.
Je, hii ndiyo njia ya hospitali? Siyo, geuka kwenye makutano yajayo.
Is this the way to the hospital? No, turn at the next junction.
For a finite verb, si- is attached to the verb and specifically indexes first-person singular in ordinary indicative negation.
| Structure | Example | Meaning |
|---|---|---|
| copula + noun | mimi si dereva | I am not a driver |
| negative subject prefix + verb | mimi siendeshi | I do not drive |
| negative possession | mimi sina gari | I do not have a car |
Mimi si mpishi, kwa hiyo sipiki chakula cha wageni.
I am not a cook, so I do not prepare the guests' food.
Separate si rejects the occupation; joined si-pik-i → sipiki negates my action. Spacing is grammatical information, not typography.
Past and future identity
Copular si normally handles a present or contextually current nonverbal relation. Explicit past and future identities use finite forms of kuwa, which carry tense and subject agreement.
Wakati huo Juma hakuwa meneja; alikuwa mhasibu.
At that time Juma was not a manager; he was an accountant.
Baada ya mafunzo haya hutakuwa mwanzilishi tena.
After this training you will no longer be a beginner.
Past ha-ku-w-a and future hu-ta-ku-w-a are verbs; they are not agreeing versions of si. See past and future copulas for the full paradigm.
Common Mistakes
Making si agree with the subject
❌ Wao hawasi madaktari wa hospitali hii.
Incorrect — copular si is invariable.
✅ Wao si madaktari wa hospitali hii.
They are not doctors at this hospital.
Joining the copula to a noun
❌ Asha sidaktari; yeye ni mfamasia.
Incorrect spacing — copular si is a separate word.
✅ Asha si daktari; yeye ni mfamasia.
Asha is not a doctor; she is a pharmacist.
Using copular si before a finite verb
❌ Mimi si ninafanya kazi Jumamosi.
Incorrect — negate the finite present verb internally.
✅ Mimi sifanyi kazi Jumamosi.
I do not work on Saturday.
Confusing identity with possession
❌ Juma si gari kwa sasa.
Wrong construction for ‘Juma does not have a car’; this says he is not a car.
✅ Juma hana gari kwa sasa.
Juma does not have a car at the moment.
Using present si for an explicit past identity
❌ Mwaka jana Amina si mkuu wa idara.
Incorrect tense for ‘was not’; use a past form of kuwa.
✅ Mwaka jana Amina hakuwa mkuu wa idara.
Last year Amina was not the head of the department.
Key Takeaways
- Separate si negates present identity, classification, properties, ownership predicates, and focused alternatives.
- It never changes for person, number, or noun class; agreement remains on nouns, adjectives, and possessives.
- Joined verbal si- means first-person “I do not,” while sina negates possession.
- Explicit past and future identity use negative forms of kuwa, not copular si.
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Start learning Swahili →Related Topics
- Negative Commands with usi-/msi-B1 — Build prohibitions with singular u- or plural m-, negative -si-, and a subjunctive-shaped verb ending.
- Negative Possession: sina, huna, hanaA1 — Use fused present negative possession by person and noun class, then switch to inflected kuwa na for past, future, and other viewpoints.
- ni for Identification and ClassificationA1 — Use invariable ni to identify people and things, name professions, and assign members to categories.
- Zero Copula with Some Property PredicatesA2 — Recognize contextual property descriptions without ni and distinguish them from locative copulas and finite property verbs.
- Past and Future Copular ClausesA2 — Build past and future copular clauses with inflected kuwa across human and noun-class subjects, including identity, property, location, possession, and existence.
- ndiyo and siyo: It Is / It Is NotA2 — Use ndiyo, siyo and their class-agreeing forms to confirm answers, identify the right referent and correct mistaken assumptions.