Το καζίνο είναι ανοιχτό όλη τη νύχτα.

Καζίνο is a neuter noun in Greek, so it takes the neuter singular article το.

• το καζίνο = the casino

This word is a loanword, and in modern Greek it is treated as neuter. That is why other words connected to it, like adjectives, also appear in the neuter form.

Because ανοιχτό must agree with το καζίνο, which is neuter singular.

The adjective ανοιχτός / ανοιχτή / ανοιχτό means open, and its form changes by gender:

• masculine: ανοιχτός
• feminine: ανοιχτή
• neuter: ανοιχτό

So:

• το καζίνο είναι ανοιχτό = the casino is open

Even though ανοιχτό comes after είναι, it still agrees with the noun it describes.

Είναι is the 3rd person singular form of είμαι (to be) in the present tense.

So:

• είμαι = I am
• είσαι = you are
• είναι = he/she/it is

In this sentence:

• Το καζίνο είναι ανοιχτό = The casino is open

Since το καζίνο is singular, Greek uses είναι.

Because ανοιχτό is a predicate adjective after the verb είναι.

In other words, the structure is:

• the casino
  • is
    • open

Greek works the same way here:

• Το καζίνο
  • είναι
    • ανοιχτό

You do not put an article before the adjective in this kind of sentence.

Literally, όλη τη νύχτα means the whole night.

It is made of:

• όλη = whole / all
• τη = the
• νύχτα = night

Together, the phrase means all night or throughout the night.

So the sentence as a whole means that the casino remains open during the entire night.

Because όλη agrees with νύχτα, and νύχτα is a feminine noun.

The adjective όλος (whole, all) changes form by gender:

• masculine: όλος
• feminine: όλη
• neuter: όλο

Since νύχτα is feminine, Greek uses όλη:

• όλη τη νύχτα = all night

In modern Greek, the feminine accusative article can appear as τη or την.

The final -ν is often dropped before many consonants, so τη νύχτα is the normal form here.

So:

• τη νύχτα = the night

You may also see την in other contexts, especially before vowels or certain consonants, but τη νύχτα is perfectly standard.

Greek often uses the accusative by itself to express duration of time.

So instead of saying something like during all the night, Greek simply says:

• όλη τη νύχτα

This is a very common pattern. Similar examples are:

• όλη μέρα = all day
• όλη την εβδομάδα = all week
• όλο το βράδυ = all evening / all night

Yes. Greek word order is more flexible than English word order.

The sentence:

• Το καζίνο είναι ανοιχτό όλη τη νύχτα

is the most neutral way to say it.

But Greek could also move the time phrase for emphasis, for example:

• Όλη τη νύχτα το καζίνο είναι ανοιχτό.

This gives more emphasis to all night.

Even when the order changes, the basic meaning stays the same.

No. You may also see ανοικτό.

Both ανοιχτό and ανοικτό mean open. In everyday modern Greek, ανοιχτό is very common and natural in speech.

So both of these are possible:

• Το καζίνο είναι ανοιχτό.
• Το καζίνο είναι ανοικτό.

For a learner, ανοιχτό is probably the form you will hear most often in conversation.

A rough pronunciation guide is:

• Το καζίνο είναι ανοιχτό όλη τη νύχτα
• to ka-ZI-no EE-ne a-nih-TO O-lee tee NEE-hta

A few helpful notes:

• ζί in καζίνο has the stress: ka-ZI-no
• είναι is pronounced roughly EE-ne
• χτ in ανοιχτό has a strong Greek h/kh sound before t
• νύχτα sounds roughly like NEE-hta

Καζίνο is commonly treated as an indeclinable loanword in everyday Greek, so it often stays the same in form.

For example:

• το καζίνο = the casino
• στο καζίνο = at the casino
• από το καζίνο = from the casino

The article changes, but καζίνο itself usually does not. This is common with many foreign loanwords in modern Greek.