Agreement with -pi 'Which?' | Swahili Grammar

The interrogative stem -pi means “which one?” or “which ones?” It does not appear as a bare word: it takes a prefix that identifies the class and number of the noun being selected. English uses the same word which with person, book, and cars; Standard Swahili distinguishes mtu yupi, kitabu kipi, and magari yapi.

Use -pi when the possible answers form a known or limited set. It normally follows an overt noun, just like other modifiers in a Swahili noun phrase. The rest of the sentence keeps its own agreement with that same head noun.

Build the form from the controlling noun

First identify the head noun and its agreement class. Then attach the appropriate pronominal or verbal-style concord to -pi. The class 1 form is the special yupi, and current Standard Swahili commonly uses wepi for class 2; wepi keeps “which people?” distinct from independent wapi, “where?” The regular class 2 form wapi also occurs, but its ambiguity with “where?” makes wepi the clearest choice in careful Standard Swahili.

Class	Typical noun	Form	Question phrase
1	mtu	yupi	mtu yupi — which person?
2	watu	wepi	watu wepi — which people?
3	mti	upi	mti upi — which tree?
4	miti	ipi	miti ipi — which trees?
5	gari	lipi	gari lipi — which car?
6	magari	yapi	magari yapi — which cars?
7	kitabu	kipi	kitabu kipi — which book?
8	vitabu	vipi	vitabu vipi — which books?
9	nyumba	ipi	nyumba ipi — which house?
10	nyumba	zipi	nyumba zipi — which houses?
11	ukurasa	upi	ukurasa upi — which page?
14	uhuru	upi	uhuru upi — which freedom?
15	kusoma	kupi	kusoma kupi — which kind or instance of reading?
16	mahali	papi	mahali papi — which place?
17	mezani	kupi	mezani kupi — at which table/location?
18	chumbani	mupi	chumbani mupi — in which room/interior?

The locative forms papi, kupi, mupi are grammatical but limited in everyday use. Papi selects a specific place, kupi a more general location or direction, and mupi an interior. In ordinary conversation, speakers very often ask simply wapi? “where?” instead. The class 15 and class 18 forms are especially uncommon outside careful explanation or contexts that make their class meaning useful.

Mti upi ulianguka wakati wa mvua?

Which tree fell during the rain?

Magari yapi yataondoka saa mbili asubuhi?

Which cars will leave at eight in the morning?

Vitabu vipi vimewekwa kwa ajili ya wanafunzi wapya?

Which books have been set aside for the new students?

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Debug from the controller outward: vitabu is class 8, so choose vipi, then check every other class-sensitive form for class 8. Do not let the nearest word or the first sound of a translation choose the prefix.

Position after the noun

With an overt head noun, -pi follows it: njia ipi, not ipi njia. The whole question phrase stays in the position where that noun phrase would normally occur. Swahili therefore does not need to move “which + noun” to the beginning as English normally does.

Ulichagua kozi ipi kwa muhula ujao?

Which course did you choose for next term?

Tutatumia ukumbi upi kwa mkutano wa kesho?

Which hall will we use for tomorrow's meeting?

Mgeni yupi amesahau simu yake hapa?

Which guest left their phone here?

Once the set is clear, the noun can be omitted and the agreeing form can stand on its own. The concord still points back to the understood class.

Kuna vikombe vitatu mezani; unataka kipi?

There are three cups on the table; which one do you want?

Nimekuletea funguo zote; zipi ni za ofisi?

I brought you all the keys; which ones are for the office?

This pronominal use does not make -pi an all-purpose translation of English which. The listener must be able to recover the omitted noun and therefore its class.

One controller, a complete concord chain

The prefix on -pi is only one link in a larger agreement chain. An adjective, a relative construction, and a finite verb each mark the class independently. Compare three otherwise parallel questions:

Mwalimu yupi mpya aliyefika jana ataanza leo?

Which new teacher who arrived yesterday will start today?

Kitabu kipi kipya kilichofika jana kitatumika leo?

Which new book that arrived yesterday will be used today?

Gari lipi jipya lililofika jana litatumika leo?

Which new car that arrived yesterday will be used today?

The controller is mwalimu in the first sentence, kitabu in the second, and gari in the third. The words are close together, but proximity is not the grammatical rule. Each dependent looks back to the head: yupi–mpya–aliye–a-, kipi–kipya–kilicho–ki-, and lipi–jipya–lililo–li-.

Human and animate nouns require a semantic check before you use the table mechanically. A person noun outside morphological class 1/2 normally takes human class 1/2 agreement: daktari yupi, madaktari wepi. See Human Semantic Agreement for the full pattern.

-pi, gani, and nani

These forms ask different kinds of questions:

Form	Agreement	Core question	Typical use
-pi	agrees with the noun	which one(s)?	selection from understood alternatives
gani	invariable	what kind / which?	open identification; very common in speech
nani	invariable pronoun	who?	asks for a person's identity, with no overt head noun

Unataka chai gani?

What kind of tea do you want?

Kati ya chai hizi, unataka ipi?

Of these teas, which one do you want?

Nani atawasilisha ripoti?

Who will present the report?

Gani and -pi overlap, and gani is frequent even where English says which. The useful distinction is discourse-based: chai gani? can ask you to identify a kind or choice openly; ipi? strongly evokes a visible, mentioned, or otherwise bounded set. Nani replaces an entire human noun phrase. If you keep the noun, ask mwanafunzi yupi?, not mwanafunzi nani? in neutral Standard Swahili.

Common Mistakes

1. Copying English order

❌ Kipi kitabu unataka?

Incorrect — -pi does not normally precede an overt noun.

✅ Unataka kitabu kipi?

Which book do you want?

2. Matching only the nearest sound instead of the head noun

❌ Kitabu yupi mpya aliyofika jana atatumika darasani?

Incorrect — every dependent has been matched to the wrong class.

✅ Kitabu kipi kipya kilichofika jana kitatumika darasani?

Which new book that arrived yesterday will be used in class?

The correction changes yupi → kipi, mpya → kipya, aliyo- → kilicho-, and a- → ki- because kitabu, not a nearby person, controls the whole chain.

3. Treating -pi as invariable

❌ Tutapanda basi ipi?

Incorrect — basi is class 5, not class 9.

✅ Tutapanda basi lipi?

Which bus will we take?

4. Using nani while retaining the human head noun

❌ Mfanyakazi nani amepiga simu?

Incorrect in a neutral identification question — nani replaces the person noun phrase.

✅ Mfanyakazi yupi amepiga simu?

Which employee called?

Use Nani amepiga simu? if you mean simply “Who called?”

5. Ignoring the ambiguity of class 2 wapi

⚠️ Wanafunzi wapi walichaguliwa?

Ambiguous — this can be understood as 'Where were the students selected?' rather than 'Which students were selected?'

✅ Wanafunzi wepi walichaguliwa?

Which students were selected?

Key Takeaways

-Pi selects from a contextually known set, follows an overt noun, and carries the controller's agreement prefix. Learn the series as a concord system rather than as unrelated vocabulary. When a sentence goes wrong, locate the head noun first and verify -pi, modifiers, relatives, and verbs from that controller outward.

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