Το κατοικίδιό μας κοιμάται ήρεμα στο κρεβάτι του.

In Modern Greek, a noun usually keeps its definite article when you use a possessive like my, your, our.

So Greek says:

το κατοικίδιό μας = literally the pet our

That is the normal way to say our pet.
Unlike English, you usually do not drop the article here.

The basic word is κατοικίδιο. When it is followed by an enclitic word like μας, Greek often adds a second written accent if the main stress is far enough from the end.

So:

• κατοικίδιο
• κατοικίδιό μας

This helps show the correct stress pattern in pronunciation. You will see the same thing in phrases like:

• το βιβλίό μου
• ο δάσκαλός μας

So the extra accent is not a different word; it is a spelling rule connected with stress.

μας here means our.

In Greek, these short possessive forms usually come after the noun:

• το σπίτι μου = my house
• ο φίλος σου = your friend
• το κατοικίδιό μας = our pet

Grammatically, μας is a weak possessive form related to the genitive. A very literal way to think of it is the pet of us.

κοιμάται is:

• 3rd person singular
• present tense
• from the verb κοιμάμαι = to sleep

So it means:

• it sleeps
• it is sleeping

depending on context.

A useful thing to notice: κοιμάμαι has middle/passive-type endings, but its meaning is active. This is very common in Greek.

It can mean either one.

Greek present tense often covers both:

• a general/habitual meaning: sleeps
• an action happening now: is sleeping

Context tells you which one is meant.
So Το κατοικίδιό μας κοιμάται can mean either Our pet sleeps or Our pet is sleeping.

Because ήρεμα is an adverb, and it describes how the pet sleeps.

• ήρεμος / ήρεμη / ήρεμο = calm, peaceful (adjective)
• ήρεμα = calmly, peacefully (adverb)

Here it modifies the verb κοιμάται, so Greek uses the adverb:

κοιμάται ήρεμα = sleeps peacefully / calmly

If you used ήρεμος, that would be describing a noun, not the action.

στο is a contraction of:

σε + το = στο

The preposition σε can mean in, on, at, to, depending on context.

So:

• στο σπίτι = in/at the house
• στο τραπέζι = on the table
• στο κρεβάτι = in/on the bed

In this sentence, English might say on its bed or sometimes in its bed, depending on the situation. Greek simply uses στο.

It is in the accusative, because σε normally takes the accusative.

The full form underneath στο κρεβάτι is:

σε το κρεβάτι

Now, with neuter nouns like κρεβάτι, the nominative and accusative singular often look the same, so you do not see a change in the ending.

Here του means its.

So:

στο κρεβάτι του = in/on its bed

Greek does not have a completely separate everyday possessive word just for its. The same short form του can mean:

• his
• its
• sometimes of him / of it

The context tells you which one is meant.

Because the noun κατοικίδιο is grammatically neuter.

Greek possessive forms follow grammatical gender:

• masculine/neuter singular possessor: του
• feminine singular possessor: της

Since κατοικίδιο is neuter, Greek refers back to it with του.

So even if the pet is biologically female, if you are referring to it with the neuter noun κατοικίδιο, του is still normal.

If you used a feminine noun such as η γάτα = the cat, then you would normally say της.

Not completely. Greek word order is more flexible than English.

This sentence has a very natural, neutral order:

Το κατοικίδιό μας κοιμάται ήρεμα στο κρεβάτι του.

That is basically:

• subject: Το κατοικίδιό μας
• verb: κοιμάται
• adverb: ήρεμα
• place phrase: στο κρεβάτι του

You can move parts around for emphasis, but the tone changes. For example:

• Το κατοικίδιό μας κοιμάται στο κρεβάτι του ήρεμα
• Ήρεμα κοιμάται το κατοικίδιό μας στο κρεβάτι του

These are possible, but less neutral or more marked. The original order is the most natural for a simple statement.

A rough pronunciation guide is:

to ka-toi-KEE-thyo mas kee-MA-tee EE-re-ma sto kre-VA-tee too

A few helpful notes:

• οι sounds like ee
• αι sounds like e
• η sounds like ee
• δ sounds like the th in this
• the stress is on the bolded syllables:
  κατοικίδιό, κοιμάται, κρεβάτι

So the rhythm is roughly:

Το κατοικίδιό μας κοιμάται ήρεμα στο κρεβάτι του.