Learn Hardcore Greek: Ανυπομονώ για τη μέρα που οι περισσότερες λέξεις θα έχουν γίνει εύκολες στο κεφάλι μου. - I look forward to the day when most words will have become easy in my head.

ανυπομονώ για + noun
- Ανυπομονώ για τη μέρα… = I can’t wait for the day…
- Ανυπομονώ για τις διακοπές. = I can’t wait for the holidays.
ανυπομονώ να + verb
- Ανυπομονώ να σε δω. = I can’t wait to see you.
- Ανυπομονώ να τελειώσω το βιβλίο. = I can’t wait to finish the book.

In your sentence we have the “για + noun” pattern: ανυπομονώ για τη μέρα.

Why is it για τη μέρα and not just τη μέρα after ανυπομονώ?

The preposition για is needed here because ανυπομονώ on its own doesn’t take a direct object the way English “I can’t wait the day” would (which is also incorrect English).

Ανυπομονώ για τη μέρα… = I’m impatient *for the day…*

So για plays the role that for does in English. Without για, ανυπομονώ τη μέρα sounds wrong in Greek.

Compare:

Ανυπομονώ για τη μέρα που… = I can’t wait for the day when…
Ανυπομονώ να έρθει η μέρα που… = I can’t wait for the day to come when…

What is the difference between μέρα and ημέρα? Could I say Ανυπομονώ για την ημέρα?

Yes, you can say Ανυπομονώ για την ημέρα που….

The difference is mainly in style:

μέρα = everyday, colloquial word (day).
ημέρα = more formal, or used in set phrases (like in official language, announcements, legal documents, some written styles).

In normal spoken Greek, τη μέρα is what you’d hear.
In a more formal or literary text, την ημέρα might sound more natural.

Why is τη μέρα in the accusative case?

Τη μέρα is in the accusative because:

It is the object of the preposition για.
Prepositions in Greek (like για, με, σε, από in modern usage) almost always take the accusative.
The article and noun agree:
- Feminine singular accusative: την / τη μέρα

So:

η μέρα (nominative, subject)
τη μέρα (accusative, object — here after για)

What is the function of που in τη μέρα που οι περισσότερες λέξεις…? Is it like when or that?

Here, που is a relative pronoun, and it works a bit like English that / when combined.

τη μέρα που… literally = the day *that…*
In natural English, you’d usually translate the whole thing as the day *when…*

So που is linking τη μέρα with the clause οι περισσότερες λέξεις θα έχουν γίνει εύκολες στο κεφάλι μου.

You could use όταν instead, but then you would slightly change the structure:

Ανυπομονώ για τη μέρα που οι περισσότερες λέξεις θα έχουν γίνει εύκολες…
Ανυπομονώ για τη μέρα όταν οι περισσότερες λέξεις θα έχουν γίνει εύκολες… (grammatical, but less common/natural than using που here)

In relative clauses after a noun like μέρα, ώρα, στιγμή, Greek strongly prefers που.

Why is it οι περισσότερες λέξεις and not something like τα περισσότερα λόγια?

Two things are going on:

λέξη vs λόγο / λόγια
- λέξεις = words in the sense of vocabulary items (what you learn in a language).
- λόγια = words more in the sense of things people say, speech, utterances.

Since the sentence is about vocabulary becoming easy in the learner’s head, λέξεις is the natural choice.

περισσότερες vs πιο πολλές
- οι περισσότερες λέξεις = most of the words
- οι πιο πολλές λέξεις = also most of the words, more colloquial, very common in speech.

Both are correct; περισσότερες is a bit more neutral/standard.

Grammatically:

λέξεις is feminine plural nominative.
περισσότερες is also feminine plural nominative, agreeing with it.
οι is the feminine plural article.

So everything matches: οι (fem pl) περισσότερες (fem pl) λέξεις (fem pl).

How should I understand θα έχουν γίνει here? Why not just θα γίνουν?

Θα έχουν γίνει is the future perfect (in meaning), while θα γίνουν is the simple future.

θα γίνουν εύκολες = they will become easy (at some point in the future)
θα έχουν γίνει εύκολες = they will have become easy (by some future point, the change will already be completed)

In your sentence:

…τη μέρα που οι περισσότερες λέξεις θα έχουν γίνει εύκολες…

The speaker imagines a future time point (τη μέρα) by which the process of becoming easy is already done.
So it matches English:

“…the day when most words *will have become easy in my head.”*

If you said θα γίνουν εύκολες, it would sound more like:

“…the day when most words *will become easy…”
(the becoming happens *on that day, not necessarily by that day).

Both are understandable; θα έχουν γίνει is a bit more precise about the idea of already being easy by then.

Can you break down θα έχουν γίνει grammatically?

Yes. The verb is γίνομαι (to become / to get / to happen).

Future perfect (here: 3rd person plural) is formed with:

θα
- present of έχω (as auxiliary) + γίνει (perfect form of γίνομαι)

So:

έχω γίνει = I have become
έχεις γίνει = you have become
έχει γίνει = he/she/it has become
έχουμε γίνει = we have become
έχετε γίνει = you (pl) have become
έχουν γίνει = they have become

Then with θα you get future perfect:

θα έχω γίνει = I will have become
θα έχουν γίνει = they will have become

In the sentence, οι περισσότερες λέξεις is plural, so the auxiliary is έχουν: θα έχουν γίνει.

Why is εύκολες in that form? What is it agreeing with?

Εύκολες is the feminine plural nominative form of the adjective εύκολος (easy).

It agrees with λέξεις, which is:

Feminine
Plural
Nominative (subject)

So you get:

οι λέξεις → οι εύκολες λέξεις
οι περισσότερες λέξεις → οι περισσότερες λέξεις είναι εύκολες

In the sentence, we have:

οι περισσότερες λέξεις θα έχουν γίνει εύκολες
= most words will have become easy

So εύκολες must match λέξεις in gender, number, and case.

What does στο κεφάλι μου literally mean, and why is it used here?

Literally:

στο κεφάλι μου = in my head

σε + το → στο, so στο κεφάλι μου = in the head of me (my head).

In this context, it expresses the mental space where words live for a language learner. It’s close to English:

easy in my head
easy for me to recall/handle in my mind.

It’s a colloquial, natural way to say that the words feel mentally easy and familiar, not just that they are objectively simple.

Could I say εύκολες για μένα instead of εύκολες στο κεφάλι μου? Is there a difference?

You could say εύκολες για μένα, and it would be correct:

…που οι περισσότερες λέξεις θα έχουν γίνει εύκολες για μένα.
= …when most words will have become easy for me.

Nuance:

εύκολες στο κεφάλι μου emphasizes your mental organization / internal feeling of the words: they “sit” well in your head, you handle them easily in your mind.
εύκολες για μένα is more general: they are easy for me, maybe because of experience, ability, or familiarity — not necessarily focusing on the image of “inside my head”.

Both are natural; στο κεφάλι μου just gives a slightly more vivid, personal image.

Why is it στο κεφάλι μου and not μέσα στο κεφάλι μου?

You could say μέσα στο κεφάλι μου (inside my head), but:

στο κεφάλι μου is shorter and completely standard.
μέσα στο κεφάλι μου adds a bit of extra emphasis on inside, which can sound more dramatic or more physical/visual.

In everyday speech about thoughts, feelings, language learning, etc., στο κεφάλι μου is the normal idiomatic choice:

Δεν μπορώ να το βάλω στο κεφάλι μου. = I can’t get it into my head.
Όλα μπερδεύονται στο κεφάλι μου. = Everything gets mixed up in my head.

Can the word order change, for example putting στο κεφάλι μου earlier in the sentence?

Yes, Greek word order is relatively flexible. You could say:

Ανυπομονώ για τη μέρα που στο κεφάλι μου οι περισσότερες λέξεις θα έχουν γίνει εύκολες.
Ανυπομονώ για τη μέρα που οι περισσότερες λέξεις στο κεφάλι μου θα έχουν γίνει εύκολες.

All are grammatically correct, but:

The original order
…που οι περισσότερες λέξεις θα έχουν γίνει εύκολες στο κεφάλι μου
sounds the most natural and smooth in everyday speech.

Moving στο κεφάλι μου earlier can sound more marked/emphatic, as if you really want to stress “in my head (not necessarily objectively)”.

Is there a more colloquial or alternative way to say this whole sentence in Greek?

Yes, several natural alternatives exist with the same idea. For example:

Ανυπομονώ για τη μέρα που οι περισσότερες λέξεις θα μου φαίνονται εύκολες.
= …when most words will seem easy to me.
Ανυπομονώ για τη μέρα που οι περισσότερες λέξεις θα βγαίνουν εύκολα.
= …when most words will come out easily.
Ανυπομονώ για τη μέρα που τα ελληνικά θα μου φαίνονται εύκολα.
= …when Greek will seem easy to me.

Your original sentence is perfectly correct and natural; these are just slightly different, very idiomatic ways a native speaker might express the same feeling.