Dayı, bana o kitabı uzatır mısın?

Dayı literally means maternal uncle. In this sentence, it is being used as a form of address, like saying Uncle, ... in English.

The comma shows that the speaker is talking to the uncle directly, not describing him.

• Dayı, bana o kitabı uzatır mısın?
• Uncle, would you pass me that book?

Also, in everyday Turkish, kinship words like dayı, abi, teyze, etc. are often used directly when addressing someone.

Ben means I, but bana means to me.

This is because Turkish adds case endings to nouns and pronouns. Here, the verb uzatmak in this context means something like to extend/pass something to someone, so the person receiving the object takes the dative ending.

• ben = I
• bana = to me

So:

• bana o kitabı uzat = pass that book to me

O here means that.

So:

• kitap = book
• o kitap = that book

In Turkish, demonstratives like bu and o come before the noun, just like this and that in English.

• bu kitap = this book
• o kitap = that book

Because kitabı has the accusative ending, which marks it as a specific direct object.

The basic noun is:

• kitap = book

But here we mean a specific book, that book, so Turkish uses the accusative:

• kitabı = the book / that book (as a direct object)

So:

• o kitap = that book
• o kitabı = that book (as the thing being passed)

This is very common in Turkish: specific direct objects usually take the accusative ending.

This is a common sound change in Turkish called consonant softening.

Some words ending in p, ç, t, k change when a vowel-initial ending is added.

Here:

• kitap
  • -ı → kitabı

So p becomes b before the vowel.

Other common examples:

• ağaç → ağacı
• kanat → kanadı
• renk → rengi

So kitabı is not irregular; it follows a normal pattern.

Uzatmak literally means to extend, to stretch out, or to hand/pass something over.

In this sentence, it means something like:

• to pass
• to hand over
• to reach over

So o kitabı uzatmak here means to pass that book.

Depending on context, uzatmak can also mean other things, such as:

• eli uzatmak = to extend a hand
• konuyu uzatmak = to drag a topic on / make it longer

Uzatır mısın? is a very common Turkish way to make a request.

Grammatically, uzatır is the aorist form, and with mısın it becomes a polite, natural request:

• uzatır mısın? = would you pass...?

By contrast:

• uzatıyor musun? usually means are you passing...? / are you extending...?

So uzatıyor musun sounds more like a question about an action in progress, not a normal request.

In many Turkish requests, the aorist + question pattern works like English would you...?

Mısın is made of two parts:

• mı/mi/mu/mü = the yes/no question particle
• -sın/sin/sun/sün = you are / second person singular marker

So:

• uzatır mısın? = would you pass? / will you pass?

Important point: in Turkish, the question particle is written separately from the verb:

• correct: uzatır mısın
• not: uzatırmısın

The vowel in mı/mi/mu/mü changes by vowel harmony. Here it is mı because of the preceding vowels in uzatır.

Yes, it is polite and natural for talking to one person you are familiar with.

It is softer than a direct command:

• Uzat! = Pass it! (more direct, can sound abrupt)

Some related forms:

• uzatır mısın? = would you pass it?
• uzatabilir misin? = could you pass it? (often even softer)
• uzatır mısınız? = would you pass it? (polite/plural)
• uzatsana = come on, pass it (casual, familiar)

So the form in your sentence is a normal everyday request.

Not necessarily. In Turkish, when directly addressing family members, people often use the bare kinship word:

• Anne!
• Baba!
• Abla!
• Dayı!

So Dayı, ... can naturally mean Uncle, ... without saying my uncle.

If you said dayım, that means my uncle, but that form is more often used when talking about him rather than calling out to him.

The sentence is:

• Dayı, bana o kitabı uzatır mısın?

A helpful breakdown is:

• Dayı = Uncle
• bana = to me
• o kitabı = that book
• uzatır mısın = would you pass

Turkish often puts the verb near the end, so this follows a typical pattern:

[address] + [recipient] + [object] + [verb/question]

A very literal order would be:

• Uncle, to me that book would-you-pass?

That sounds strange in English, but it is normal in Turkish.

Yes. Turkish word order is flexible, although some orders sound more natural than others depending on emphasis.

For example:

• Dayı, bana o kitabı uzatır mısın? = neutral/natural
• Dayı, o kitabı bana uzatır mısın? = also natural
• Bana o kitabı uzatır mısın, dayı? = also possible, with a different tone

The main meaning stays the same, but changing the order can shift the focus or emphasis.

For learners, the original order is a very good standard pattern to remember.

Yes, if the context already makes it clear.

For example:

• Dayı, o kitabı uzatır mısın? = Uncle, would you pass that book?

This still works, and the listener may understand from context that the speaker means to me.

But bana is included when the speaker wants to make the recipient explicit, or simply because that is the natural way they chose to say it.

You would use mısınız instead of mısın.

• Dayı, bana o kitabı uzatır mısın? = to one person, familiar
• ... uzatır mısınız? = more polite, or to more than one person

So:

• Bana o kitabı uzatır mısınız? = Would you pass me that book?

This is useful because Turkish often uses the plural/formal siz forms to show politeness.