Demonstrative Case Forms: How Bu, Şu, and O Change With Case

Bu kitap (“this book”) and bunu istiyorum (“I want this”) both use the same little word for “this” — but the word itself changes shape between them. Once a demonstrative stops being the subject of a sentence and starts being acted on, given to, found inside, or taken from, it declines through case exactly like a noun does, with one small twist of its own.

What these words do

Turkish has three demonstratives, each marking distance from the speaker and listener:

• bu — this (close to the speaker)
• şu — that (near the listener, or something the speaker is pointing out for the first time, regardless of actual distance)
• o — that/it (far from both speaker and listener, or something already mentioned — this is the same o that doubles as the third-person pronoun “he/she/it”)

Used as a bare subject or in front of a noun, all three stay in this plain form: Bu pahalı. (“This is expensive.”) O kitap benim. (“That book is mine.”) The moment one of them takes a case ending instead, a buffer consonant steps in first.

Forming it

Before any case suffix that starts with a vowel-adjacent sound, bu, şu, and o all insert a buffer -n-, then take the normal case ending from vowel harmony (the same endings covered in the dative, accusative, ablative, and locative lessons):

• Bunu masaya koy. — Put this on the table. (accusative)
• Şuna bak. — Look at that. (dative)
• Kitap onda. — The book is with him/her. (locative, possession sense — see below)
• Ondan bir şey öğrendim. — I learned something from that/him/her. (ablative)
• Bunun rengi çok güzel. — This one’s color is very nice. (genitive)

Notice the genitive row: onun is the same word you’ve already met as the possessive determiner “his/her/its” — because that’s exactly what it is, the genitive of the demonstrative/pronoun o. Bunun and şunun work the identical way for “this one’s” and “that one’s.”

Exceptions worth knowing

The plural forms don’t need the buffer at all. Bunlar, şunlar, and onlar (“these,” “those,” “those/they”) already end in the consonant -r, so case suffixes attach directly the same way they would to any consonant-final noun: bunlara (dative, “to these”), bunları (accusative, “these”), bunlarda (locative, “in/on these”), bunlardan (ablative, “from these”) — no -n- anywhere in the plural paradigm.

The locative form of o, onda, carries a second, very common meaning beyond “in/on that.” Turkish uses it idiomatically to say someone currently has or is holding something: Kalem onda. (“The pen is with him/her” — literally “the pen is in/on him/her.”) This possession sense shows up constantly in everyday speech and is worth learning as its own pattern, not just a literal location.

Şu is about attention, not just distance. While bu is “close” and o is “far,” şu is best understood as “the thing I’m about to point your attention to” — a speaker reaching for a car key on the table in front of both people might still say şunu alman gerek (“you need to take that”) rather than bunu, because şu signals “look here, this specific one,” independent of exact distance.

Examples

• Bunu sen mi aldın? — Did you buy this?
• Şunu bana uzatır mısın? — Could you hand that to me?
• Onu hiç tanımıyorum. — I don’t know him/her at all.
• Param onda, benim üzerimde yok. — The money is with him/her, I don’t have it on me.
• Bundan sonra daha dikkatli olacağım. — I’ll be more careful from now on (literally “from this on”).
• Bu çocukların oyuncakları şunlardan daha pahalı. — These children’s toys are more expensive than those (ones).

Each sentence pairs the right demonstrative with the case the verb or preposition-like ending demands — the buffer -n- (singular) is there every time a case suffix follows, and absent every time the plural -lar/-ler already supplies a consonant to land on.

Try it yourself

Babi, Speafy’s AI tutor, will walk you through swapping bu, şu, and o across every case in the same sentence frame until the buffer -n- stops feeling like an extra step, and Speafy’s FSRS-based flashcards make sure the onda-as-possession pattern sticks alongside its plain locative meaning instead of being forgotten in favor of the more obvious one.