Δεδομένου ότι υπάρχει καθυστέρηση απόπλου, περιμένουμε.

Δεδομένου ότι is a formal linking expression meaning given that, considering that, or sometimes since.

In this sentence, it introduces the reason/background for the main action:

• Δεδομένου ότι υπάρχει καθυστέρηση απόπλου, περιμένουμε.
• Given that there is a departure delay, we are waiting.

It is more formal than everyday connectors like:

• επειδή = because
• αφού = since / as
• μιας και = since / given that

Δεδομένου is the genitive singular form of δεδομένος, which originally means given.

In Δεδομένου ότι, this has become a fixed formal expression, so learners should usually treat the whole phrase as a set phrase meaning:

• given that
• considering that

You do not need to analyze it every time when reading. In practice, δεδομένου ότι functions like a conjunction introducing a subordinate clause.

Here ότι means that and introduces the full clause:

• υπάρχει καθυστέρηση απόπλου

So the structure is:

• Δεδομένου ότι
  • clause

This is similar to English:

• Given that there is a delay...
• Considering that there is a delay...

So ότι is the word that connects the formal expression to the statement that follows.

Υπάρχει means there is / exists.

It is 3rd person singular because the thing that exists is singular:

• καθυστέρηση = delay

So:

• υπάρχει καθυστέρηση = there is a delay

If the noun were plural, Greek would use the plural verb:

• υπάρχουν καθυστερήσεις = there are delays

After υπάρχει, Greek often leaves out the article when talking about something indefinite or introducing it for the first time.

So:

• υπάρχει καθυστέρηση = there is a delay

This is very natural Greek.

If you used the article:

• υπάρχει η καθυστέρηση

that would usually sound more specific, as if both speaker and listener already know exactly which delay is being discussed. In this sentence, the indefinite meaning fits better.

Καθυστέρηση απόπλου means departure delay or more literally delay of departure.

• καθυστέρηση = delay
• απόπλου = of departure / of sailing

Απόπλου is in the genitive because it depends on the noun καθυστέρηση. Greek often uses the genitive after nouns to show a relationship like of ....

So this is basically:

• delay of departure

This noun + genitive structure is especially common in formal Greek.

Not exactly. Απόπλους is a more specific and formal word, especially associated with ships or sailing/departure by sea.

So this sentence sounds like something from:

• a port announcement
• a ferry notice
• an official travel context

For more general departure, Greek often uses:

• αναχώρηση = departure

So depending on context, you might also see:

• καθυστέρηση αναχώρησης = departure delay

But απόπλου is perfectly appropriate if the context is maritime.

Περιμένουμε is present tense, 1st person plural: we wait / we are waiting.

Greek present tense can cover both:

• a general present: we wait
• an ongoing present: we are waiting

The exact English translation depends on context. In this sentence, the most natural English is probably:

• we are waiting

because it sounds like a current situation caused by the delay.

Greek often leaves out subject pronouns because the verb ending already shows who the subject is.

Here:

• περιμένουμε already means we wait / we are waiting

So εμείς is not necessary.

You could add εμείς for emphasis:

• Δεδομένου ότι υπάρχει καθυστέρηση απόπλου, εμείς περιμένουμε.

But that would sound more contrastive, like we are waiting, perhaps unlike someone else.

The word order is not completely fixed.

This sentence begins with the reason/background clause:

• Δεδομένου ότι υπάρχει καθυστέρηση απόπλου, περιμένουμε.

That is very natural in formal Greek.

You could also put the main clause first:

• Περιμένουμε, δεδομένου ότι υπάρχει καθυστέρηση απόπλου.

This is also understandable, though the original order feels a bit more natural for this formal style.

Greek word order is generally more flexible than English, but changes in order can slightly change emphasis.

The comma separates the introductory subordinate clause from the main clause.

Structure:

• Δεδομένου ότι υπάρχει καθυστέρηση απόπλου = subordinate clause
• περιμένουμε = main clause

So the comma helps show:

• background/reason first
• main statement second

This is normal punctuation in Greek, especially when the subordinate clause comes first.

It is natural, but it sounds formal and somewhat written or official.

A native speaker in casual speech would often choose something simpler, such as:

• Αφού υπάρχει καθυστέρηση απόπλου, περιμένουμε.
• Επειδή υπάρχει καθυστέρηση απόπλου, περιμένουμε.

Or even more naturally in everyday speech:

• Έχει καθυστέρηση ο απόπλους, οπότε περιμένουμε.

So your original sentence is correct, but it has an official or formal tone.

Yes, in many contexts you could.

Compare:

• Δεδομένου ότι υπάρχει καθυστέρηση απόπλου, περιμένουμε.
  = formal, official, written

• Επειδή υπάρχει καθυστέρηση απόπλου, περιμένουμε.
  = straightforward because

• Αφού υπάρχει καθυστέρηση απόπλου, περιμένουμε.
  = natural since / as

The meaning is similar, but the register changes.
If you want to sound formal, δεδομένου ότι is a good choice.
If you want to sound conversational, επειδή or αφού is more common.