Αυτό είναι ένα μόσχευμα.

In this sentence, αυτό is being used as a demonstrative pronoun, meaning this.

So Αυτό είναι ένα μόσχευμα is literally:

• Αυτό = this
• είναι = is
• ένα μόσχευμα = a graft / a transplant

Greek αυτό can also mean it in some contexts, but here the sentence is clearly identifying something, so this is the natural interpretation.

A useful comparison:

• Αυτό είναι καλό. = This is good.
• Το βλέπω. = I see it.

Greek often uses other structures, like το, for it as an object.

Because μόσχευμα is a neuter noun.

In Greek, the indefinite article a/an changes according to gender:

• ένας = masculine
• μία / μια = feminine
• ένα = neuter

Since μόσχευμα is neuter, it takes ένα:

• ένα μόσχευμα

This is one of the first things to check when learning a new Greek noun: its gender.

A big clue is the ending -μα.

Many Greek nouns ending in -μα are neuter, for example:

• το γράμμα = the letter
• το όνομα = the name
• το πρόβλημα = the problem
• το μόσχευμα = the graft / transplant

So when you see μόσχευμα, it is very likely neuter, and that matches the article ένα.

Its dictionary form would normally appear as:

• το μόσχευμα

Yes. In a sentence like this, Greek normally uses the verb είμαι = to be, just like English does.

Here:

• είναι = is

So the structure is very similar to English:

• Αυτό είναι ένα μόσχευμα.
• This is a graft.

Greek does not usually drop the verb to be in this kind of sentence.

Είναι is the third person singular form of είμαι (to be) in the present tense.

In this sentence, it matches αυτό:

• αυτό = this / it
• είναι = is

So together:

• αυτό είναι = this is

A few present-tense forms of είμαι are:

• είμαι = I am
• είσαι = you are
• είναι = he/she/it is

Also, είναι can serve for they are in Modern Greek, depending on context.

Yes. Αυτό is the subject here.

The sentence breaks down like this:

• Αυτό = subject
• είναι = verb
• ένα μόσχευμα = predicate noun / complement

So the sentence identifies what this is.

In English grammar terms, this works like:

• This is a doctor.
• This is a book.
• This is a graft.

Yes, Greek word order is more flexible than English, but Αυτό είναι ένα μόσχευμα is the most neutral and natural order here.

You may also see variations for emphasis, such as:

• Ένα μόσχευμα είναι αυτό.

But that sounds marked or emphatic, not like the normal basic way to say it.

For learners, the safest default is:

• subject + verb + complement

So:

• Αυτό είναι ένα μόσχευμα.

In most normal situations, you would include ένα.

• Αυτό είναι ένα μόσχευμα. = This is a graft.

Leaving out the article can sound unnatural if you mean a graft as a countable thing.

Greek often uses articles more consistently than English. So if English says a graft, Greek normally wants:

• ένα μόσχευμα

You might omit the article only in special contexts, such as definitions, labels, or very compressed speech, but that is not the standard beginner pattern.

A simple learner-friendly pronunciation is:

• af-TO EE-ne e-NA MO-shev-ma

A slightly more careful breakdown:

• Αυτό → stress on the second syllable: αυ-ΤΟ
• είναι → usually sounds like EE-ne
• ένα → stress on the first syllable: E-na
• μόσχευμα → stress on the first syllable: MO-shev-ma

The stress marks show you where the voice should fall:

• Αυτό
• είναι
• ένα
• μόσχευμα

The accent marks in Greek show which syllable is stressed.

In this sentence:

• Αυτό → stress on -τό
• είναι → stress on εί-
• ένα → stress on έ-
• μόσχευμα → stress on μό-

Stress matters in Greek pronunciation and spelling, so accents are important and should be learned as part of the word.

For an English speaker, it helps to think of them as pronunciation guides that are also part of correct writing.

They are related, but not the same form.

• αυτός = masculine form, often this/he
• αυτή = feminine form, often this/she
• αυτό = neuter form, often this/it

Here we have αυτό because the idea is this thing, which is neuter.

Examples:

• Αυτός είναι γιατρός. = He / This man is a doctor.
• Αυτή είναι δασκάλα. = She / This woman is a teacher.
• Αυτό είναι ένα μόσχευμα. = This is a graft.

So αυτό is the neuter form.

It is a real and useful word, but it is more likely to appear in medical, scientific, or technical contexts than in casual everyday conversation.

It can refer to a graft or transplant, depending on context.

For example, it may be used for:

• a tissue graft
• a skin graft
• a transplant material

So a learner should understand it, but it is not one of the most basic daily nouns like book, house, or food.

The definite article form is:

• το μόσχευμα = the graft / the transplant

Since the noun is neuter singular, it takes το as the definite article.

So you can compare:

• ένα μόσχευμα = a graft
• το μόσχευμα = the graft

This is a good way to memorize Greek nouns: learn them with the article.

So instead of learning only μόσχευμα, it is better to learn:

• το μόσχευμα

Not always. Greek has different ways to express this, depending on grammar and style.

In a sentence like this, Αυτό είναι... is very natural when you are pointing something out or identifying it:

• Αυτό είναι ένα μόσχευμα. = This is a graft.

But if this modifies a noun directly, Greek often uses forms like:

• αυτό το βιβλίο = this book
• αυτή η πόλη = this city
• αυτό το μόσχευμα = this graft

So:

• Αυτό είναι ένα μόσχευμα. = This is a graft.
• Αυτό το μόσχευμα είναι νέο. = This graft is new.

The first is a pronoun; the second is a determiner before a noun.