Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον.

The book is thin, but it is very interesting.

Breakdown of Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον.

• είμαι: to be
• πολύ: very
• αλλά: but
• το βιβλίο: the book
• ενδιαφέρων: interesting
• λεπτός: thin

Questions & Answers about Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον.

What does each Greek word correspond to in English in this sentence?

The sentence Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον. can be mapped as:

• Το = the (definite article, neuter singular)
• βιβλίο = book
• είναι = is (3rd person singular of the verb είμαι = to be)
• λεπτό = thin (or slim)
• αλλά = but
• είναι = is (repeated for the second clause)
• πολύ = very (here it works as an adverb)
• ενδιαφέρον = interesting

Natural translation: The book is thin, but it is very interesting.

Why is the article Το used, and why is it το and not ο or η?

Greek articles agree in gender, number, and case with the noun:

• Το is the neuter, singular, nominative definite article.
• βιβλίο (book) is a neuter noun in the nominative singular form.

So you must use το βιβλίο (the book).
Other forms:

• ο = masculine, singular, nominative (e.g. ο άντρας = the man)
• η = feminine, singular, nominative (e.g. η γυναίκα = the woman)

Since βιβλίο is neuter, it takes το.

Why is the adjective λεπτό in that form? What is it agreeing with?

Adjectives in Greek agree with the noun they describe in gender, number, and case.

• Noun: το βιβλίο → neuter, singular, nominative
• Adjective: λεπτό → neuter, singular, nominative

So you get:

• Το βιβλίο είναι λεπτό. = The book is thin.

If the noun changed, the adjective would change:

• Ο τοίχος είναι λεπτός. (masculine, singular) = The wall is thin.
• Η σελίδα είναι λεπτή. (feminine, singular) = The page is thin.
• Τα βιβλία είναι λεπτά. (neuter plural) = The books are thin.

What is the difference between λεπτό and μικρό?

Both can be translated as small in some contexts, but they describe different qualities:

• λεπτό = thin, slim (focus on thickness)

  • ένα λεπτό βιβλίο = a thin book (not many pages)
  • ένα λεπτό κομμάτι χαρτί = a thin piece of paper

• μικρό = small, little (focus on overall size, not thickness)

  • ένα μικρό βιβλίο = a small book (physically small, maybe small format)
  • ένα μικρό παιδί = a small/young child

In this sentence, λεπτό means the book doesn’t have many pages or is not thick, not necessarily that it is small in height/width.

Why do we repeat είναι in αλλά είναι πολύ ενδιαφέρον? Could we omit the second είναι?

Both are possible:

1. Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον.
2. Το βιβλίο είναι λεπτό, αλλά πολύ ενδιαφέρον.

In Greek:

• Repeating είναι (version 1) is completely correct and clear.
• Omitting είναι in the second part (version 2) is also natural, because the form of είναι is understood from the first clause.

Spoken Greek often prefers the shorter version:
Το βιβλίο είναι λεπτό, αλλά πολύ ενδιαφέρον.

So you are allowed to drop the second είναι, but you don’t have to.

Why is there no word for it in the second part (but it is very interesting)?

Greek is a pro‑drop language: subject pronouns (I, you, he, she, it, we, they) are usually omitted when the subject is clear from context or from the verb form.

• In English you must say: it is very interesting.
• In Greek you normally do not say αυτό είναι πολύ ενδιαφέρον here, because the subject (το βιβλίο) is already established.

So:

• Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον.
  Literally: The book is thin, but is very interesting.
  The subject it is understood as το βιβλίο.

What is πολύ exactly? Why is it πολύ and not another form?

πολύ comes from the adjective πολύς / πολλή / πολύ (much, many).

In this sentence, πολύ modifies an adjective (ενδιαφέρον) and functions as an adverb meaning very.

• As an adverb, it always appears as πολύ (invariable form):
  • πολύ ενδιαφέρον = very interesting
  • πολύ καλός = very good
  • πολύ ακριβό = very expensive

When πολύς / πολλή / πολύ is used as an adjective (meaning much, many), it changes form and agrees with the noun:

• πολύς χρόνος = much time (masc.)
• πολλή ζάχαρη = a lot of sugar (fem.)
• πολλά βιβλία = many books (neut. plural)

So in είναι πολύ ενδιαφέρον, πολύ is the adverb form = very.

Why is ενδιαφέρον in that form and not ενδιαφέροντα or ενδιαφέρων?

Here ενδιαφέρον is an adjective meaning interesting, and it must agree with το βιβλίο:

• το βιβλίο → neuter, singular, nominative
• ενδιαφέρον → neuter, singular, nominative

Some related forms you might see:

• ενδιαφέρων = masculine, nominative singular (more formal, used mostly before nouns, e.g. ένας ενδιαφέρων άνθρωπος = an interesting person)
• ενδιαφέροντα can be:
  • neuter plural: ενδιαφέροντα βιβλία = interesting books
  • or accusative singular masculine in some contexts

In everyday speech, for το βιβλίο you say:

• Το βιβλίο είναι ενδιαφέρον. = The book is interesting.

Is the comma before αλλά used the same way as the comma before but in English?

Yes, very similar.

• In English: The book is thin, but it is very interesting.
• In Greek: Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον.

You normally place a comma before αλλά when it connects two clauses with different or contrasting statements.
You do not put a comma after αλλά.

Can I change the word order and still be correct? For example, Το βιβλίο είναι πολύ ενδιαφέρον αλλά λεπτό?

You have some flexibility, but not all orders sound equally natural.

Correct and natural variants:

• Το βιβλίο είναι λεπτό, αλλά πολύ ενδιαφέρον.
• Το βιβλίο είναι πολύ ενδιαφέρον, αλλά λεπτό.
• Το βιβλίο είναι λεπτό αλλά πολύ ενδιαφέρον. (without comma in informal writing)

Your example Το βιβλίο είναι πολύ ενδιαφέρον αλλά λεπτό is grammatically fine and understandable.
The difference is mostly in emphasis:

• First version emphasizes that the book is thin, then adds the interesting contrast.
• Second version leads with very interesting, and then adds thin as a kind of surprise or extra information.

Greek tends to keep adjectives after είναι, just as shown: είναι λεπτό, είναι πολύ ενδιαφέρον.

How do you pronounce είναι and why is it written with so many vowels?

είναι is pronounced approximately [ˈine] (EE-neh).

Spelling:

• ει is pronounced like English ee (as in see)
• αι is pronounced like English e (as in bed)

So:

• είναι = /íne/ → EE-neh

Historically, Greek had more distinct vowel sounds, but in modern Greek several vowel combinations (ει, οι, η, υ, ι) all sound like i, and αι sounds like e. The spelling keeps the older distinctions.

What form of the verb είμαι is είναι?

είναι is the 3rd person singular and plural, present tense, active voice of the verb είμαι (to be).

Present tense of είμαι:

• (εγώ) είμαι = I am
• (εσύ) είσαι = you are (singular)
• (αυτός/αυτή/αυτό) είναι = he/she/it is
• (εμείς) είμαστε = we are
• (εσείς) είστε / είσαστε = you are (plural / polite)
• (αυτοί/αυτές/αυτά) είναι = they are

So in this sentence, είναι means is (referring to το βιβλίο).

Could I also say Το λεπτό βιβλίο είναι πολύ ενδιαφέρον? Is there any difference?

Yes, that is correct Greek:

• Το λεπτό βιβλίο είναι πολύ ενδιαφέρον. = The thin book is very interesting.

Difference in structure:

• Το βιβλίο είναι λεπτό → predicate adjective (you say what the book is)
• Το λεπτό βιβλίο → attributive adjective (you describe the noun directly, which book)

Difference in meaning/emphasis:

• Το βιβλίο είναι λεπτό, αλλά είναι πολύ ενδιαφέρον.
  
  • You state two facts about the same book: it is thin, but (surprisingly) very interesting.
• Το λεπτό βιβλίο είναι πολύ ενδιαφέρον.
  
  • You identify which book you’re talking about (the thin one) and say that this one is very interesting. There is no explicit contrast with something else.

Both are grammatically correct; they just organize information slightly differently.