Arkadaşım sözünü tuttu.

It breaks down like this:

• Arkadaşım = my friend
• sözünü = his/her promise or his/her word as the direct object
• tuttu = kept

So the sentence follows the common Turkish pattern subject + object + verb.

The base word is arkadaş, meaning friend.

The ending -ım is the first-person singular possessive suffix, so it adds the meaning my.

• arkadaş = friend
• arkadaşım = my friend

This is very common in Turkish. Instead of using a separate word for my, Turkish often adds a suffix to the noun.

Because the sentence is talking about a specific promise/word, not just promise in a general sense.

In Turkish, a definite direct object often takes the accusative ending. Also, söz here is possessed, because it is someone’s word/promise.

So sözünü includes more information than plain söz:

• söz = word, promise
• sözünü = his/her promise, as the object of the verb

In this expression, Turkish normally uses the possessed form because the promise belongs to someone.

In this sentence, the most natural analysis is:

• söz = word, promise
• -ü = his/her
• -n- = linking consonant
• -ü = accusative ending

So:

• sözü = his/her word, promise
• sözünü = his/her word, promise + definite object marking

This is why the word looks longer than the English equivalent.

That n is a very common linking consonant in Turkish.

When a noun already has a third-person possessive ending and then another ending is added, Turkish often inserts -n- to connect them smoothly.

So:

• sözü = his/her promise
• sözünü = his/her promise + accusative

That -n- helps link the two endings.

Yes, the form sözünü can be ambiguous by itself.

It can represent either:

• your promise as the object
• his/her promise as the object

Turkish often leaves this to context.

In Arkadaşım sözünü tuttu, the natural meaning is usually My friend kept his/her promise, because that is the normal meaning of the idiom in context.

That is a very common learner question.

Yes, tutmak often means to hold, to catch, or to keep depending on context. In the fixed expression sözünü tutmak, it means to keep one’s word or to keep a promise.

So this is best learned as a whole chunk:

• söz vermek = to make a promise
• sözünü tutmak = to keep a promise

If you translate word by word too literally, it may feel strange, but as an idiom it is completely normal.

Tuttu is the simple past tense.

It comes from tutmak:

• dictionary form: tutmak
• stem: tut-
• past tense: tuttu

So tuttu means kept.

In the third person singular, Turkish does not need an extra ending here, so tuttu by itself can mean he kept, she kept, or it kept, depending on context.

Because the most neutral Turkish word order is usually subject + object + verb.

So:

• Arkadaşım = subject
• sözünü = object
• tuttu = verb

This makes Arkadaşım sözünü tuttu the most natural basic order.

Turkish word order can change for emphasis, but for learners, putting the verb at the end is the safest default.

No. Turkish does not mark grammatical gender in this sentence.

• arkadaşım can mean my male friend or my female friend
• tuttu does not show he or she

So English has to choose he or she, or use they, based on context. Turkish itself leaves that unspecified.

Yes, very common.

It is one of the standard ways to say to keep one’s word or to keep a promise.

A few related expressions are:

• söz vermek = to promise
• sözünü tutmak = to keep one’s promise
• sözünü tutmamak = not to keep one’s promise

So this is a very useful expression to memorize as a set phrase.

Here are the common forms:

• Arkadaşım sözünü tutmadı. = My friend did not keep his/her promise.
• Arkadaşım sözünü tuttu mu? = Did my friend keep his/her promise?

So:

• tuttu = kept
• tutmadı = did not keep
• tuttu mu = did ... keep?

These are very useful patterns to practice with other verbs too.