Η υπεύθυνη δήλωση είναι απαραίτητη.

Η is the feminine singular definite article, meaning the.

It appears here because δήλωση is a feminine singular noun, so the article has to match it:

• η δήλωση = the declaration

Since υπεύθυνη describes δήλωση, the whole noun phrase becomes:

• η υπεύθυνη δήλωση = the responsible/official declaration

In Greek, articles are used very often, sometimes more often than in English.

Because it is a feminine singular adjective, and it must agree with δήλωση, which is also feminine singular.

So:

• δήλωση = feminine singular noun
• υπεύθυνη = feminine singular adjective

This is called agreement. In Greek, adjectives usually match the noun in:

• gender
• number
• case

Here both are feminine, singular, nominative.

For the same reason: it refers to the subject η υπεύθυνη δήλωση, so it must agree with it.

In this sentence:

• η υπεύθυνη δήλωση = the subject
• είναι απαραίτητη = is necessary

Even though απαραίτητη comes after είναι, it still describes the feminine singular subject, so it takes the feminine singular form.

Compare:

• Το έγγραφο είναι απαραίτητο. = The document is necessary.
• Η δήλωση είναι απαραίτητη. = The declaration is necessary.

Είναι is the verb to be.

Here it means is.

So the structure is:

• Η υπεύθυνη δήλωση = the subject
• είναι = is
• απαραίτητη = necessary

A useful thing to remember is that είναι can mean:

• is
• are

depending on the subject.

Examples:

• Η δήλωση είναι απαραίτητη. = The declaration is necessary.
• Τα έγγραφα είναι απαραίτητα. = The documents are necessary.

Sometimes, yes, especially in:

• headings
• notices
• bureaucratic language
• very compressed written style

So you may sometimes see:

• Η υπεύθυνη δήλωση απαραίτητη

But in normal standard Greek, Η υπεύθυνη δήλωση είναι απαραίτητη is the full and natural sentence.

So for learners, it is safest to include είναι unless you have a specific reason not to.

Yes. Υπεύθυνη δήλωση is a very common official expression in Greek, especially in administration and legal/bureaucratic contexts.

Although word-for-word it looks like responsible declaration, in practice it refers to a formal statement/declaration made by a person, often signed and used for official purposes.

So learners should treat υπεύθυνη δήλωση as a set phrase, not just as any random adjective + noun combination.

Yes, Greek word order is more flexible than English word order.

The neutral order here is:

• Η υπεύθυνη δήλωση είναι απαραίτητη.

But Greek can also move words around for emphasis. For example:

• Απαραίτητη είναι η υπεύθυνη δήλωση.

This puts more emphasis on απαραίτητη.

Even so, the original order is the most straightforward and learner-friendly one.

The main noun phrase η υπεύθυνη δήλωση is in the nominative, because it is the subject of the sentence.

So:

• η = feminine singular nominative article
• υπεύθυνη = feminine singular nominative adjective
• δήλωση = feminine singular nominative noun

And απαραίτητη is also in the nominative because it is a predicate adjective describing the subject after είναι.

So the sentence is a good example of nominative agreement across the subject and predicate adjective.

The accent mark shows which syllable is stressed.

So the stress falls like this:

• υπεύθυνη → stress on -πεύ-
• δήλωση → stress on δή-
• απαραίτητη → stress on -ραί-

Greek spelling marks stress clearly, and this is very important for pronunciation.

If you ignore the accent marks, your Greek may still be understood, but it will sound less natural and sometimes may cause confusion.

A rough pronunciation for an English speaker is:

• ee ee-PEF-thi-nee DHEE-lo-see EE-ne a-pa-RAI-ti-ti

A few notes:

• η sounds like ee
• υπ here sounds like ep because υ is pronounced i, and before voiceless consonants the ευ combination is pronounced ef
• δήλωση has the dh sound of this, not the d of dog
• είναι is usually pronounced EE-ne

If you want to sound more natural, focus especially on the stressed syllables.

Because Greek adjectives change form to match the noun they describe.

English says:

• necessary declaration
• the declaration is necessary

with necessary unchanged.

Greek usually changes the adjective ending depending on the noun:

• απαραίτητος = masculine
• απαραίτητη = feminine
• απαραίτητο = neuter

So here it must be απαραίτητη because it refers to η δήλωση, which is feminine.

In literal grammar terms, someone might try to interpret it that way, but in real Greek usage υπεύθυνη δήλωση is a standard set term.

So in context, Greek speakers usually understand it as an official kind of declaration, not just any declaration connected with responsibility.

That is why it is best to learn υπεύθυνη δήλωση as one vocabulary unit.