Learn Hardcore Greek: Το δωμάτιό μου είναι καθαρό σήμερα, αλλά το γραφείο μου είναι λίγο βρώμικο. - My room is clean today, but my desk is a little dirty.

When you add the enclitic pronoun μου (my) after a word that is stressed on the third syllable from the end (a proparoxytone like δωμάτιο), Greek spelling adds a second accent on the last syllable of the noun:

το δωμάτιο → το δωμάτιό μου

So you see two written accents:

one on μά, the original stress of the word
one on ό, added because of the weak pronoun μου that follows

This is a spelling rule of Modern Greek with enclitic pronouns; the pronunciation does not have two strong separate stresses in normal speech, it just keeps the main stress where it was.

What exactly does μου mean, and why does it come after the noun instead of before like in English?

μου here means my. It is a weak possessive pronoun that normally comes after the noun:

το δωμάτιό μου = my room
το γραφείο μου = my desk / my office

Greek does not use a separate possessive adjective like English my, your before the noun. Instead, you use:

the definite article (το, η, ο etc.)
- the noun
- the weak pronoun (μου, σου, του, της, μας, σας, τους)

Example patterns:

το βιβλίο μου = my book
η τσάντα σου = your bag
ο φίλος του = his friend

μου itself does not change form for gender or number; the article and the noun show those.

Why is the article το used with both δωμάτιο and γραφείο?

το is the neuter singular definite article in Greek. Both δωμάτιο (room) and γραφείο (desk / office) are neuter nouns, so they take το:

το δωμάτιο = the room
το γραφείο = the desk / the office

Neuter nouns typically end in:

-ο (like δωμάτιο, γραφείο, βιβλίο)
-ι (like παιδί, child)

The article changes with gender:

ο for masculine singular (e.g. ο φίλος – the friend)
η for feminine singular (e.g. η πόρτα – the door)
το for neuter singular (e.g. το δωμάτιο, το γραφείο)

Why do καθαρό and βρώμικο both end in -ο here?

Adjectives in Greek must agree with the noun they describe in:

gender (masculine / feminine / neuter)
number (singular / plural)
case (here, nominative)

Both δωμάτιο and γραφείο are neuter singular, nominative case, so the adjectives must also be neuter singular nominative:

το δωμάτιο → το δωμάτιό μου είναι καθαρό
(καθαρό = neuter singular)
το γραφείο → το γραφείο μου είναι βρώμικο
(βρώμικο = neuter singular)

If the noun were feminine, the endings would change, for example:

η κουζίνα είναι καθαρή (The kitchen is clean.)
η τσάντα είναι βρώμικη (The bag is dirty.)

What is the difference between δωμάτιο and γραφείο?

Meanings:

το δωμάτιο = the room (any kind of room: bedroom, hotel room, etc.)
το γραφείο has two common meanings:
- desk (the piece of furniture)
- office (the place where you work)

In the sentence:

το δωμάτιό μου είναι καθαρό σήμερα = my room is clean today
το γραφείο μου είναι λίγο βρώμικο = my desk is a bit dirty
(Here γραφείο is naturally understood as desk, because it is being described as dirty in contrast to the clean room.)

Context usually makes it clear whether γραφείο means desk or office.

Where can σήμερα go in the sentence? Is the position fixed?

σήμερα means today, and it is fairly flexible in word order. All of these are possible and natural:

Το δωμάτιό μου είναι καθαρό σήμερα.
Σήμερα το δωμάτιό μου είναι καθαρό.
Το δωμάτιό μου σήμερα είναι καθαρό. (a bit more emphatic)

The most neutral-sounding options are usually:

Σήμερα το δωμάτιό μου είναι καθαρό.
Το δωμάτιό μου είναι καθαρό σήμερα.

So the word order is not fixed; you can move σήμερα to change rhythm or emphasis, without changing the basic meaning.

What does λίγο do here, and why does it come before βρώμικο?

λίγο means a little, a bit, slightly. Here it modifies the adjective βρώμικο (dirty):

λίγο βρώμικο = a bit dirty, slightly dirty

In Greek, adverbs like λίγο, πολύ (very), αρκετά (quite) usually go before the adjective they modify:

πολύ καθαρό = very clean
αρκετά μεγάλο = quite big
λίγο βρώμικο = a bit dirty

If you put λίγο after the adjective (βρώμικο λίγο), it sounds unusual or wrong in standard modern usage in this kind of sentence.

Why is there a comma before αλλά?

αλλά means but, and it connects two clauses:

Το δωμάτιό μου είναι καθαρό σήμερα,
αλλά
το γραφείο μου είναι λίγο βρώμικο.

In Greek writing, it is very common (and usually recommended) to put a comma before αλλά when it links two full clauses, just like in English:

My room is clean today, but my desk is a bit dirty.

So the comma marks the break between the two contrasting statements.

How is βρώμικο pronounced, and what about the spelling βρόμικο?

Pronunciation in simple terms: [vró-mi-ko].

β = v
ρ = r (trilled or tapped)
ώ = stressed o sound
μι = mi
κο = ko

There are two accepted spellings in Modern Greek:

βρώμικο
βρόμικο

They are both pronounced the same in everyday speech. βρώμικο is a more traditional / archaic-looking spelling; βρόμικο is also common and accepted. In your sentence, βρώμικο is perfectly correct.

Can I drop είναι in this sentence, like some languages drop the verb “to be”?

In Modern Greek, you generally cannot omit είναι (is / am / are) in this kind of sentence. You need it for a normal, correct sentence:

Το δωμάτιό μου είναι καθαρό σήμερα. ✅
Το δωμάτιό μου καθαρό σήμερα. ❌ (wrong or at least very incomplete)

Greek does sometimes omit είμαι forms in very specific, mostly fixed expressions (for example on signs or in headlines), but in everyday spoken or written sentences like yours, you should keep είναι.