Learn Hardcore Greek: Το μαχαίρι είναι ανάμεσα στα πιάτα στο τραπέζι. - The knife is between the plates on the table.

Το – the (neuter singular definite article)
μαχαίρι – knife
είναι – is (3rd person form of to be)
ανάμεσα – between / in the middle
στα – in/on/at the (contraction of σε + τα, used with plural neuter nouns)
πιάτα – plates (plural of πιάτο, plate)
στο – in/on/at the (contraction of σε + το, used with singular neuter nouns)
τραπέζι – table

So the structure is literally: The knife is between in-the plates on-the table.
Natural English: The knife is between the plates on the table.

Why do we say Το μαχαίρι with the, instead of just μαχαίρι (“knife”) like in English sometimes?

Greek uses the definite article (ο, η, το) much more consistently than English when talking about specific things.

Το μαχαίρι = the knife, a specific knife that both speaker and listener can identify (for example, the one on the table in front of you).
Just μαχαίρι without an article is usually more general or indefinite (like saying “knife” as a concept, or in some very specific patterns).

In English we might sometimes drop the in instructions (“Put knife between plates”), but in Greek, when you mean a particular knife in a real situation, you almost always use the article: Το μαχαίρι.

What gender and number are μαχαίρι, πιάτα, and τραπέζι, and what are their basic forms?

All three nouns here are neuter, which is one of the three grammatical genders in Greek (masculine, feminine, neuter).

μαχαίρι – neuter, singular
- Basic dictionary form: το μαχαίρι (the knife)
πιάτα – neuter, plural
- Singular: το πιάτο (the plate)
- Plural: τα πιάτα (the plates)
τραπέζι – neuter, singular
- Basic dictionary form: το τραπέζι (the table)

In this sentence:

Το μαχαίρι is the subject (neuter singular).
στα πιάτα and στο τραπέζι are prepositional phrases with neuter nouns governed by σε.

Because they’re neuter, the nominative and accusative forms look the same (e.g. το πιάτο / το πιάτο, τα πιάτα / τα πιάτα).

What exactly is είναι, and why this form of the verb?

είναι is the present tense form of the verb είμαι (to be). It is used for:

he / she / it is
they are
also the polite you are (formal εσείς είστε / είσαστε is more precise, but είναι appears in some polite constructions)

Here, the subject is το μαχαίρι (the knife), which is third person singular, so είναι translates as is:

Το μαχαίρι είναι… = The knife is…

What does ανάμεσα mean, and how is it used? Is it like μεταξύ?

ανάμεσα means between / in the middle (of).

Usage in this sentence:

ανάμεσα στα πιάτα = between the plates

Grammatically, ανάμεσα is an adverb that is almost always followed by σε + article/noun phrase:

ανάμεσα σε δύο καρέκλες – between two chairs
ανάμεσα στα πιάτα – between the plates

μεταξύ also means between / among, but:

It is a bit more formal or “written” in style.
It usually takes the genitive case directly, without σε:
- μεταξύ των πιάτων – between the plates

So you could say:

Το μαχαίρι είναι ανάμεσα στα πιάτα… (very common, neutral)
Το μαχαίρι είναι μεταξύ των πιάτων… (more formal/literary)

What is στα, and why do we use it instead of just σε?

στα is a contraction (a combined form) of:

σε + τα → στα

σε is a very common preposition meaning in / on / at / to, depending on context.
When σε is followed by the definite article, it usually contracts:

σε + το → στο (in/on/at the – singular neuter)
σε + τα → στα (in/on/at the – plural neuter)
σε + τον → στον (masculine singular)
σε + την → στην (feminine singular), etc.

In our sentence:

στα πιάτα = σε + τα πιάτα → στα πιάτα → in/on/among the plates
στο τραπέζι = σε + το τραπέζι → στο τραπέζι → on/at the table

You normally use the contracted forms (στο, στα, στον, στην), not the separated ones, in everyday speech and writing.

Why do we use στα πιάτα and στο τραπέζι with this case? What case is it?

In Modern Greek, almost all prepositions, including σε, govern the accusative case.

So strictly speaking:

στα πιάτα – accusative plural neuter
στο τραπέζι – accusative singular neuter

However, for neuter nouns, the nominative and accusative forms look the same:

το πιάτο – nominative/accusative singular
τα πιάτα – nominative/accusative plural
το τραπέζι – nominative/accusative singular

So you can’t see the case from the noun form alone; you infer it from the grammar rule “after σε, use accusative”. The presence of the preposition σε (in its contracted forms στο, στα, etc.) tells you that those nouns are in accusative.

Is the word order fixed? Could I say Το μαχαίρι στο τραπέζι είναι ανάμεσα στα πιάτα instead?

The word order in Greek is fairly flexible, especially for elements like prepositional phrases. Your version is possible and correct:

Το μαχαίρι στο τραπέζι είναι ανάμεσα στα πιάτα.

This puts a bit more emphasis on στο τραπέζι (on the table), as if clarifying which knife:

The knife on the table is between the plates (as opposed to some other knife).

The original:

Το μαχαίρι είναι ανάμεσα στα πιάτα στο τραπέζι.

flows more like a single description of the knife’s location: between the plates on the table. Both are grammatical; what changes slightly is what you emphasize.

Could I use μεταξύ instead of ανάμεσα and still be correct?

Yes, you can, but you must adjust the structure:

Το μαχαίρι είναι μεταξύ των πιάτων στο τραπέζι.

Key differences:

μεταξύ usually takes genitive:
- των πιάτων (of the plates), not τα πιάτα.
It sounds a bit more formal or “bookish” than ανάμεσα.

So:

Everyday / neutral speech: ανάμεσα στα πιάτα
More formal / written style: μεταξύ των πιάτων

Meaning-wise in this context, they are practically the same.

How would I say A knife is between the plates on the table instead of The knife…?

For a knife, you use the neuter singular indefinite article ένα:

Ένα μαχαίρι είναι ανάμεσα στα πιάτα στο τραπέζι.
= A knife is between the plates on the table.

Note:

Greek has an indefinite article (ένας, μία/μια, ένα) only in the singular.
For plural, Greek usually drops the article:
- Μαχαίρια είναι ανάμεσα στα πιάτα στο τραπέζι.
  = Knives are between the plates on the table. (no some in Greek, just the bare plural)

So:

Το μαχαίρι… – The knife… (specific)
Ένα μαχαίρι… – A knife… (non‑specific)

Is there any difference between saying στο τραπέζι and πάνω στο τραπέζι?

Both are common and often interchangeable, but there’s a slight nuance:

στο τραπέζι – literally “at/on the table”; context tells you if it’s on, at, near, etc. Very general and very common.
πάνω στο τραπέζι – literally “on top of the table”; emphasizes that the object is on the surface of the table.

In many everyday situations:

Το μαχαίρι είναι στο τραπέζι.
Το μαχαίρι είναι πάνω στο τραπέζι.

both will be understood as “The knife is on the table.”
Your original sentence would then be:

Το μαχαίρι είναι ανάμεσα στα πιάτα πάνω στο τραπέζι.
(The knife is between the plates on top of the table.)