Learn Hardcore Greek: Μου αρέσει να ακούω πιάνο όταν χαλαρώνω στο σπίτι. - I like to listen to piano when I relax at home.

αρέσω literally means “to be pleasing”.
So the thing that is liked is the subject, and the person who likes it appears in the genitive (often called “indirect object” for learners).

In Μου αρέσει...:

αρέσει = “is pleasing” (3rd person singular)
μου = “to me”

So Μου αρέσει... = “It is pleasing to me…” → “I like…”

You don’t say Εγώ αρέσω το πιάνο. That would be like saying in English “I am pleasing the piano.”

What exactly does μου mean in Μου αρέσει? Is it “me” or “my”?

Μου is the weak (clitic) genitive form of εγώ (I).

It can correspond to English “to me” or “my”, depending on context.
Here, in Μου αρέσει..., it means “to me”:

μου = to me
αρέσει = is pleasing

So the literal structure is:
[To me] [is pleasing] [to listen to piano when I relax at home].

When μου means “my”, it follows a noun:

το βιβλίο μου = my book

Here, since it comes before the verb αρέσει, it works like “to me”.

What is the role of να in να ακούω? Is that an infinitive?

Modern Greek no longer has an infinitive form like “to listen”.
Instead, it uses να + verb to express many of the functions that English uses an infinitive for.

να ακούω corresponds roughly to “to listen / to hear” in this context.
Technically, να introduces a subjunctive form of the verb.

In Μου αρέσει να ακούω πιάνο...:

να ακούω = “to listen (habitually / generally)”

So while learners often call it “the infinitive”, it’s grammatically a subjunctive clause introduced by να.

Why is it ακούω and not ακούσω after να? What’s the difference?

Greek verbs have aspect:

ακούω = imperfective aspect (ongoing, habitual, repeated)
ακούσω = perfective aspect (single, complete event)

After μου αρέσει να..., when we talk about something we like in general or habitually, we almost always use the imperfective:

Μου αρέσει να ακούω πιάνο.
= I like listening to piano (in general / as an activity).

If you said:

Μου αρέσει να ακούσω πιάνο.

it would sound odd, because να ακούσω refers to a single, complete act of listening, not the general activity.

So να ακούω is correct here because we’re describing a general preference.

Why is there no article before πιάνο? Why not το πιάνο?

In Greek, when you talk about an activity involving an instrument in a general sense, you often omit the article:

ακούω πιάνο = I listen to piano (piano music in general)
παίζω πιάνο = I play piano

If you add the article:

ακούω το πιάνο
this usually suggests a specific piano (e.g. this particular piano here), or sounds less natural in the “general music” sense.

In your sentence, the meaning is “I like listening to piano music (in general)”, so πιάνο is used without an article.

What is the subject of αρέσει in this sentence?

The subject of αρέσει is the whole clause να ακούω πιάνο όταν χαλαρώνω στο σπίτι.

Structurally:

Μου = to me (experiencer)
αρέσει = is pleasing
να ακούω πιάνο όταν χαλαρώνω στο σπίτι = what is pleasing (the thing I like / the activity)

So grammatically, the entire “to listen to piano when I relax at home” clause acts as the subject of the verb αρέσει.

That’s why αρέσει is 3rd person singular: it agrees with that whole clause as a singular “thing”.

Could I also say Μου αρέσει όταν χαλαρώνω στο σπίτι να ακούω πιάνο? Is that correct?

Yes, it’s grammatically possible, but it sounds less natural and a bit clunky.

Μου αρέσει να ακούω πιάνο όταν χαλαρώνω στο σπίτι.
= Very natural, smooth word order.
Μου αρέσει όταν χαλαρώνω στο σπίτι να ακούω πιάνο.
= Understandable, but the word order is heavier and less idiomatic.

Greek usually prefers να ακούω πιάνο to be right after Μου αρέσει, and then adds όταν χαλαρώνω στο σπίτι as a time clause at the end.

What does όταν χαλαρώνω express here? Is it present tense, and why?

Yes, χαλαρώνω is in the present tense, imperfective aspect.

όταν χαλαρώνω στο σπίτι = “when I (am) relaxing at home / when I relax at home”

The present imperfective expresses:

a repeated, habitual situation: every time I’m relaxing at home,
I like listening to piano.

Using a perfective form (e.g. όταν χαλαρώσω) would point to a single completion of relaxing and wouldn’t fit the habitual meaning here. So όταν χαλαρώνω is the natural choice.

Why is it στο σπίτι and not σε το σπίτι?

στο is a contraction of:

σε (in, at, to) + το (the, neuter singular)

So:

σε το σπίτι → στο σπίτι = “at home / in the house”

Similarly:

σε τον δρόμο → στον δρόμο
σε την πόλη → στην πόλη

In normal speech and writing, the contracted forms (στο, στον, στην, στα, στους, στις) are always used.

Could I drop στο and just say όταν χαλαρώνω σπίτι?

Normally, no—you should keep στο here:

όταν χαλαρώνω στο σπίτι is the standard, natural phrasing.

Omitting στο and saying χαλαρώνω σπίτι can occur colloquially in some contexts, especially with μένω σπίτι (“I stay home”), but with χαλαρώνω it sounds incomplete or dialectal.

As a learner, it’s better (and safer) to use στο σπίτι.

How would the meaning change if I said Μου αρέσει να παίζω πιάνο instead of να ακούω πιάνο?

να ακούω πιάνο = “to listen to piano (music)”
να παίζω πιάνο = “to play piano”

So:

Μου αρέσει να ακούω πιάνο = I like listening to piano.
Μου αρέσει να παίζω πιάνο = I like playing the piano.

The grammar is the same (μου αρέσει + να + verb), only the activity changes.

Is πιάνο masculine, feminine, or neuter? And what case is it in here?

πιάνο is a neuter noun, indeclinable in practice (it usually stays πιάνο in all cases in everyday usage).

In να ακούω πιάνο:

πιάνο is the direct object of ακούω, so it’s in the accusative (which for this word looks the same as the nominative).

How is the sentence stressed and pronounced?

The stress pattern (stressed syllables in caps):

ΜΟΥ α-ΡΕ-σει να α-ΚΟΥ-ω ΠΙΑ-νο Ο-ταν χα-λα-ΡΩ-νω στο ΣΠΙ-τι

Rough pronunciation (in simple English terms):

Μου – “moo”
αρέσει – “a-REH-see”
να – “na” (short a, as in “father”)
ακούω – “a-KOO-o” (often sounding like “a-KOO” in fast speech)
πιάνο – “PYA-no” (with a py sound, like “pya”)
όταν – “O-tan”
χαλαρώνω – “ha-la-RO-no” (χ = a rough h, like German “Bach”)
στο – “sto”
σπίτι – “SPEE-tee”

The main intonation peak is usually around αρέσει or πιάνο, depending on what you emphasize in context.