Ο ενδιαφερόμενος περιμένει στο γραφείο διαβατηρίων.

Literally, ο ενδιαφερόμενος means the interested one / the person concerned.

In everyday or official Greek, it often means:

• the applicant
• the interested party
• the person concerned

So here it is not just someone who is casually interested; it usually refers to the person whose case or request is being handled.

It is originally a participle of the verb ενδιαφέρομαι (to be interested).

But in this sentence it is being used like a noun, because it has the article ο in front of it:

• ο ενδιαφερόμενος = the interested person / the applicant

This is very common in Greek: an adjective or participle can become a noun when used with the definite article.

Ο is the masculine singular nominative definite article, meaning the.

It shows that ενδιαφερόμενος is:

• masculine
• singular
• the subject of the sentence

So:

• ο ενδιαφερόμενος = the applicant / the person concerned

If it were feminine, you would get:

• η ενδιαφερόμενη

Περιμένει is:

• present tense
• 3rd person singular
• from the verb περιμένω = to wait

So it means:

• he/she is waiting
• he/she waits

In this sentence, English would usually translate it as is waiting.

Στο is the contracted form of:

• σε + το = στο

So:

• σε = in / at / to
• το = the (neuter singular)
• στο = in the / at the / to the

This contraction is completely normal in Modern Greek.

After σε, Modern Greek normally uses the accusative case.

The noun γραφείο is neuter, and in the singular its nominative and accusative forms are the same:

• nominative: το γραφείο
• accusative: το γραφείο

So after στο, you still see γραφείο.

Literally it means:

• γραφείο = office
• διαβατηρίων = of passports

So the whole phrase is literally office of passports, which in natural English is passport office.

Greek often uses this structure:

• noun + genitive

to express something that English often expresses with a noun used like an adjective.

Διαβατηρίων is the genitive plural of διαβατήριο (passport).

The basic forms are:

• το διαβατήριο = the passport
• τα διαβατήρια = the passports
• διαβατηρίων = of passports

So in γραφείο διαβατηρίων, the genitive shows the relation:

• office of passports
• meaning passport office

Because διαβατηρίων is being used as a general classifier, not to mean some specific passports.

So:

• γραφείο διαβατηρίων = passport office / office for passports

If you added an article, such as των, it would sound more like:

• the office of the passports which suggests a specific set of passports, not the general function of the office.

In institutional names and fixed expressions, Greek very often leaves out the article in this kind of genitive phrase.

Here it can correspond to either in or at, depending on how English phrases it.

So:

• στο γραφείο διαβατηρίων can be understood as at the passport office
• and sometimes also in the passport office

In natural English, at the passport office is usually the best translation.

Yes. Greek word order is more flexible than English.

This sentence has a neutral order:

• Ο ενδιαφερόμενος περιμένει στο γραφείο διαβατηρίων.

But you could also say:

• Στο γραφείο διαβατηρίων περιμένει ο ενδιαφερόμενος.

That would put more emphasis on the location: At the passport office, the applicant is waiting.

The original version is the most straightforward, neutral way to say it.

A rough pronunciation is:

o en-dia-fe-RO-me-nos pe-ri-ME-ni sto gra-FI-o dhia-va-ti-RI-on

A few useful points:

• γρ in γραφείο starts with a voiced sound like a soft gh
• δ in διαβατηρίων sounds like th in this, not th in thin
• the stress is marked by the written accent:
  • ενδιαφερόμενος
  • περιμένει
  • γραφείο
  • διαβατηρίων