Τα μηχανήματα σταματούν ταυτόχρονα.

• Τα = the
• μηχανήματα = machines
• σταματούν = stop / are stopping
• ταυτόχρονα = simultaneously / at the same time

So the structure is basically:

Τα μηχανήματα + σταματούν + ταυτόχρονα
The machines + stop/are stopping + simultaneously

Because μηχάνημα is a neuter noun, and here it is plural.

Its basic forms are:

• singular: το μηχάνημα = the machine
• plural: τα μηχανήματα = the machines

So τα is the correct plural neuter article.

The singular is μηχάνημα.

So:

• το μηχάνημα = the machine
• τα μηχανήματα = the machines

This is a very common neuter noun pattern in Greek:

• singular in -μα
• plural in -ματα

For example:

• το πρόβλημα → τα προβλήματα
• το γράμμα → τα γράμματα

Because the subject is plural: the machines.

σταματούν is the 3rd person plural form of σταματώ (to stop).

So:

• σταματά = it stops / is stopping
• σταματούν = they stop / are stopping

Since τα μηχανήματα is plural, the verb must match it.

It is the present tense.

In Greek, the present tense can often mean either:

• a general/habitual action: The machines stop simultaneously
• an action happening now: The machines are stopping simultaneously

The exact English translation depends on context.

The dictionary form is σταματώ or sometimes σταματάω, depending on the dictionary.

Both mean to stop.

So:

• dictionary form: σταματώ / σταματάω
• sentence form: σταματούν

Here it is intransitive.

That means it does not take a direct object here. The machines themselves are doing the stopping:

• Τα μηχανήματα σταματούν. = The machines stop.

Greek σταματώ can also be used transitively in some contexts, but in this sentence it simply means to come to a stop.

ταυτόχρονα is an adverb here.

It tells us how the action happens:

• σταματούν = they stop
• ταυτόχρονα = simultaneously

So it modifies the verb.

Yes. It means:

• simultaneously
• at the same time

In this sentence, both are natural translations.

Because it is being used as an adverb, and adverbs do not change for gender, number, or case.

So even though μηχανήματα is plural, ταυτόχρονα stays the same.

The neutral, most straightforward order is:

Τα μηχανήματα σταματούν ταυτόχρονα.

Greek word order is more flexible than English, though. You could move things around for emphasis, for example:

• Τα μηχανήματα ταυτόχρονα σταματούν.
• Ταυτόχρονα σταματούν τα μηχανήματα.

But the original sentence is the most neutral and natural for a learner.

Because it is the noun phrase that matches the plural verb σταματούν, and semantically it makes sense as the thing performing the action.

In English, the machines are what stop, so they are the subject.

Also, the sentence has no direct object, so τα μηχανήματα is naturally understood as the subject.

Yes, Greek often drops subject pronouns, but not usually full noun subjects when they carry important information.

For example, Greek can say:

• Σταματούν ταυτόχρονα. = They stop simultaneously / They are stopping simultaneously.

But if you specifically want to say the machines, you keep:

• Τα μηχανήματα σταματούν ταυτόχρονα.

Yes, if you mean the machines.

Greek uses the definite article very regularly, often more than English does. So:

• Τα μηχανήματα = the machines

Without τα, the phrase would not normally mean the same thing in a neutral sentence.

A simple pronunciation guide is:

ta mi-ha-NI-ma-ta sta-ma-TOON taf-TO-hro-na

A few notes:

• χ in μηχανήματα and ταυτόχρονα is a throat sound, like the ch in German Bach
• ου in σταματούν sounds like oo
• αυ in ταυτόχρονα sounds like af here, because it comes before a voiceless consonant

The stress falls on:

• μηχανήματα
• σταματούν
• ταυτόχρονα

Potentially, yes, depending on context.

The core meaning of σταματούν is stop / come to a stop, but in real-world context with machines, English might sometimes translate it more naturally as:

• The machines stop at the same time
• The machines are stopping at the same time
• The machines shut down at the same time

The best English wording depends on what kind of machines and situation you are talking about.

Not normally, because simultaneously / at the same time usually implies more than one action or thing.

Grammatically, the singular parts would be:

• το μηχάνημα = the machine
• σταματά = stops / is stopping

So the singular sentence would be:

• Το μηχάνημα σταματά. = The machine stops.

You would only use ταυτόχρονα with the singular if there were another action happening at the same time and the context made that clear.