O bunu iddia etti.

Yes. O is a third-person singular pronoun and does not mark gender, so it can mean he, she, or it, depending on context.

Also, in other contexts o can mean that, but in this sentence it is functioning as the subject pronoun.

That is true: Turkish often leaves out subject pronouns when the subject is clear from context.

So O bunu iddia etti could often be shortened to Bunu iddia etti.

Including o can add:

• clarity: to make the subject explicit
• contrast: He/She claimed this, not someone else
• emphasis: drawing attention to who made the claim

This is especially useful because etti by itself does not tell you gender, and third-person singular has no special ending that identifies the subject as clearly as some other persons do.

Bunu is bu plus the accusative ending.

• bu = this
• bunu = this as a direct object

So in this sentence, bunu is the thing being claimed.

Because the object is specific/definite, Turkish uses the accusative case.

English does not mark this kind of thing on nouns very much, but Turkish does. A specific object usually gets accusative marking.

Here, bu is not just any vague this; it is a specific thing being referred to, so bunu is the natural form.

With demonstratives and some pronouns, Turkish often uses an extra n before case endings.

So:

• bu
  • accusative does not become buyu
• it becomes bunu

You will see the same pattern in forms like:

• buna
• bunda
• bundan
• bunun

That n is just part of how these words connect to suffixes.

It is a very common Turkish structure: a noun plus the auxiliary verb etmek.

• iddia = claim
• etmek = to do / to make as a light verb in many expressions

So iddia etmek literally behaves like to make a claim, but it is used as the standard way to say to claim.

Only the auxiliary verb changes for tense and person:

• iddia ediyor = is claiming
• iddia etti = claimed
• iddia etmiş = apparently claimed / is said to have claimed

So it is a fixed expression, but still written as two words.

Because it comes from:

• et- = the verb stem
• past tense suffix = -ti / -tı / -tu / -tü after a voiceless consonant

Since the stem already ends in t, and the suffix also begins with t, they come together as etti.

So this is basically:

• et- + -ti = etti

The double t is not random; it comes from the stem and the suffix meeting.

Because the neutral word order in Turkish is usually Subject – Object – Verb.

So:

• O = subject
• bunu = object
• iddia etti = verb phrase

That makes O bunu iddia etti a very normal, neutral Turkish sentence.

English usually prefers Subject – Verb – Object, so this often feels backwards to English speakers at first.

Yes, Turkish word order is flexible, but changes usually affect emphasis or focus, not the basic meaning.

For example:

• O bunu iddia etti.
  Neutral: He/She claimed this.

• Bunu o iddia etti.
  Focus on o: It was he/she who claimed this.

• Bunu iddia etti.
  Subject omitted because it is understood from context.

The most neutral version is still the original one. In many cases, the verb or verb phrase still tends to stay near the end.

Not exactly.

• söylemek = to say / tell
• iddia etmek = to claim / assert

İddia etmek often suggests that someone is making a statement that may be challenged, doubted, or presented as their assertion rather than an accepted fact.

So if you use iddia etti, it can carry a nuance like:

• they claimed
• they asserted
• they said something in a way that may not be fully accepted as true

That makes it stronger and more specific than just söyledi.