Ψάχνω κάποιον που να είναι διαθέσιμος απόψε, γιατί η φίλη μου είναι πιεσμένη και δεν μπορεί να έρθει.

Because κάποιον is the accusative singular form of κάποιος (someone / somebody).

The verb ψάχνω (I’m looking for) takes a direct object, so Greek uses the accusative:

• κάποιος = someone (subject form, nominative)
• κάποιον = someone (object form, accusative)

So:

• Κάποιος είναι εδώ. = Someone is here.
• Ψάχνω κάποιον. = I’m looking for someone.

In this sentence, the speaker is looking for someone, so κάποιον is required.

This is a very common learner question. Here, που να είναι expresses the idea of someone who would be / who may be / who is expected to be available, rather than referring to a specific known person.

So:

• που είναι διαθέσιμος = who is available
  This sounds more like you have a definite person in mind, or you are stating a fact.

• που να είναι διαθέσιμος = who is available / who might be available / who would be available
  This is more natural when the person is indefinite, unknown, or being sought.

Because the speaker says Ψάχνω κάποιον... (I’m looking for someone...), Greek often uses this pattern:

• κάποιον που να + subjunctive

It suggests a desired or suitable person, not an already identified one.

να είναι is the subjunctive form of the verb είμαι (to be).

• είναι by itself can mean he/she/it is
• να είναι means something like to be / may be / be, depending on context

Greek uses να very often before verbs in subordinate clauses. It does not always translate neatly into one English word.

In this sentence:

• που να είναι διαθέσιμος = literally something like who to be available, but naturally: who is available / who might be available

So the important thing is not a word-for-word translation, but the function: να είναι helps create the idea of a suitable, sought-after person.

Because it agrees with κάποιον, which is grammatically masculine singular.

Greek adjectives must agree with the noun or pronoun they describe in:

• gender
• number
• case

Here:

• κάποιον = masculine singular accusative
• διαθέσιμος is the dictionary form, but after να είναι Greek often keeps the predicate adjective in the nominative form conceptually linked to the person being described

The key point for learners is that the adjective matches the person being referred to. Since κάποιον is masculine singular, the adjective is masculine singular too.

If the sentence referred to a woman, you might see:

• Ψάχνω κάποια που να είναι διαθέσιμη.

Απόψε means tonight.

It is a single adverb and is very common in everyday Greek.

So:

• απόψε = tonight
• σήμερα το βράδυ = this evening / tonight

Both can work in many contexts, but απόψε is shorter and very natural in speech.

Examples:

• Τι κάνεις απόψε; = What are you doing tonight?
• Θα βγούμε σήμερα το βράδυ. = We’ll go out tonight / this evening.

In your sentence, απόψε fits naturally because the speaker is talking about availability for tonight.

Literally, yes, it comes from the idea of being pressed. But in real usage, είμαι πιεσμένος / πιεσμένη usually means:

• under pressure
• stressed
• swamped
• pressed for time

So in this sentence, η φίλη μου είναι πιεσμένη means something like:

• my friend is under pressure
• my friend is stressed
• my friend is tied up / overwhelmed

It usually refers to pressure from work, obligations, time, or stress.

Because φίλη is feminine, the adjective is feminine too:

• masculine: πιεσμένος
• feminine: πιεσμένη

Both are possible, but η φίλη μου is very normal Greek.

Greek often uses the definite article with possessives:

• η φίλη μου = my friend
• literally: the friend of mine

This is one of the big differences from English. Greek commonly says:

• το σπίτι μου = my house
• ο αδερφός μου = my brother
• η φίλη μου = my friend

Sometimes the article can be omitted in certain contexts, but in a sentence like this, keeping it is the most standard choice.

Έρθει is the aorist subjunctive form of έρχομαι (to come), used here after να.

So:

• μπορεί να έρθει = can come
• δεν μπορεί να έρθει = cannot come

This is very standard Greek:

• μπορώ να πάω = I can go
• μπορεί να μιλήσει = he/she can speak
• μπορούμε να δούμε = we can see

Why έρθει and not έρχεται?

• έρχεται = he/she is coming / comes (indicative)
• να έρθει = to come / come after να, often with modal verbs like μπορώ

So after μπορεί να, Greek normally uses this kind of να + verb structure.

Because γιατί introduces the reason: because.

The sentence has two parts:

1. Ψάχνω κάποιον που να είναι διαθέσιμος απόψε
2. γιατί η φίλη μου είναι πιεσμένη και δεν μπορεί να έρθει

The comma helps separate the main statement from the explanation.

In English, this would also often take a comma:

• I’m looking for someone available tonight, because my friend is stressed and can’t come.

In Greek, punctuation with γιατί is very common when the reason clause follows after a full main clause.

Yes, in this sentence που works like who.

So:

• κάποιον που να είναι διαθέσιμος = someone who is available

But it is worth knowing that Greek που is very flexible. It can correspond to:

• who
• that
• which

depending on the context.

Examples:

• ο άνθρωπος που μιλάει = the person who is speaking
• το βιβλίο που διάβασα = the book that I read

So here, που is the relative word introducing the description of κάποιον.

It can be used for both.

With people, it often means:

• available
• free
• able to make time

Example:

• Είσαι διαθέσιμος αύριο; = Are you available tomorrow?

With things, it can mean:

• available
• in stock
• accessible

Example:

• Το προϊόν δεν είναι διαθέσιμο. = The product is not available.

In your sentence, it clearly refers to a person being free/available tonight.

Yes, but the meaning would shift a little.

• διαθέσιμος = available
• ελεύθερος = free

For people, both can sometimes work, but διαθέσιμος is often better when talking about being available for a task, help, an appointment, or plans.

Compare:

• Είσαι διαθέσιμος απόψε; = Are you available tonight?
• Είσαι ελεύθερος απόψε; = Are you free tonight?

Both are natural, but διαθέσιμος can sound slightly more practical or schedule-related.

Also, ελεύθερος can have other meanings, such as:

• free as in not occupied
• single
• free/liberated

So διαθέσιμος is the safer and clearer word here.

Not necessarily.

Greek often uses the masculine singular as the default form when the person is unknown or unspecified.

So:

• κάποιον
• διαθέσιμος

do not necessarily mean the speaker wants a man. They can simply refer to someone in a general sense.

If the speaker specifically meant a woman, Greek would normally use feminine forms:

• Ψάχνω κάποια που να είναι διαθέσιμη απόψε...

If the gender is unknown or irrelevant, the masculine is often used as the default grammatical form.

A useful way to break it down is:

• Ψάχνω κάποιον
  I’m looking for someone

• που να είναι διαθέσιμος απόψε
  who is available tonight

• γιατί
  because

• η φίλη μου είναι πιεσμένη
  my friend is under pressure / stressed

• και δεν μπορεί να έρθει
  and can’t come

So the full structure is:

main clause + relative clause + reason clause

That makes this a very good example of how Greek connects ideas naturally:

1. what the speaker wants,
2. what kind of person they want,
3. why they want that person.