Ο κάτοχος διαβατηρίου περιμένει στο γραφείο διαβατηρίων.

Ο is the definite article meaning the.

Here it shows that κάτοχος is:

• masculine
• singular
• nominative (the subject form)

So ο κάτοχος = the holder.

Greek articles change for gender, number, and case, much more than English the does.

Κάτοχος means holder, owner, or possessor, depending on context.

In this sentence, it means passport holder.

A few useful forms:

• ο κάτοχος = the male holder / the holder (masculine)
• η κάτοχος = the female holder

So if you were talking specifically about a woman, you would usually say:

Η κάτοχος διαβατηρίου περιμένει...

Because it is in the genitive singular of διαβατήριο (passport).

Greek often uses the genitive to mean of ... or to show a relationship like possession or classification.

So:

• κάτοχος = holder
• διαβατηρίου = of a passport / passport

Together:

• κάτοχος διαβατηρίου = holder of a passport = passport holder

This is very natural Greek.

Great question. Both patterns exist, but they mean slightly different things.

• κάτοχος διαβατηρίου = passport holder in a general/classifying sense
• κάτοχος του διαβατηρίου = holder of the passport, referring to a specific passport

So in official or general phrasing, Greek often leaves out the article in expressions like this.

Compare:

• κάτοχος διαβατηρίου = passport holder
• ο κάτοχος του διαβατηρίου = the holder of the passport

Περιμένει is the 3rd person singular present form of περιμένω (to wait).

So it means:

• he/she/it waits
• he/she is waiting

Greek present tense can cover both the English simple present and present continuous, so context decides which translation sounds best.

Because Greek works differently from English here.

In Greek, περιμένω often takes a direct object with no preposition:

• Περιμένω τον φίλο μου. = I’m waiting for my friend.

So English wait for someone is usually just:

• περιμένω κάποιον

In your sentence, there is no object at all, so it simply means:

• is waiting

Στο is just the very common contraction of:

• σε + το = στο

So:

• σε το γραφείο becomes στο γραφείο

This means in the office or at the office, depending on context.

You will see this all the time in Greek:

• στο = σε + το
• στη = σε + τη(ν)
• στον = σε + τον

Because after σε (or contracted στο), Greek normally uses the accusative.

The noun γραφείο has the same form in nominative and accusative singular, so it looks unchanged.

So:

• το γραφείο = the office
• στο γραφείο = in/at the office

Even though the form looks the same, grammatically it is functioning as accusative after σε.

Because this is another very common Greek noun pattern:

• γραφείο = office
• διαβατηρίων = of passports

So literally:

• γραφείο διαβατηρίων = office of passports

In natural English, that is usually:

• passport office
• passport department

The genitive plural here shows what kind of office it is: an office dealing with passports in general.

Because the two phrases express different ideas:

• κάτοχος διαβατηρίου = a person defined by having a passport / being a passport holder
• γραφείο διαβατηρίων = an office concerned with passports in general

So:

• singular genitive in the first phrase
• plural genitive in the second phrase

This is not random; it reflects the meaning of each expression.

Yes, Greek word order is more flexible than English.

The neutral order here is:

• Ο κάτοχος διαβατηρίου περιμένει στο γραφείο διαβατηρίων.

But Greek could also say:

• Στο γραφείο διαβατηρίων περιμένει ο κάτοχος διαβατηρίου.

That version puts more focus on where the waiting is happening.

Because Greek marks grammar with articles and case endings, it can move parts around more easily than English can.