Ο εγκέφαλος λειτουργεί συνεχώς.

ο is the definite article, meaning the.

Here it agrees with εγκέφαλος and tells you that the noun is:

• masculine
• singular
• nominative (the subject form)

Greek uses the definite article more often than English does. In general statements like this one, Greek often says ο εγκέφαλος where English might say either the brain or just talk about brain more generally.

ο εγκέφαλος is:

• masculine
• singular
• nominative

It is the subject of the sentence, so nominative is the expected case.

Also, -ος is a very common ending for masculine nouns in Greek, though it is not exclusively masculine in all cases. In this sentence, the article ο makes it clear that εγκέφαλος is masculine.

In standard Greek, Ο εγκέφαλος λειτουργεί συνεχώς sounds much more natural.

Leaving out the article and saying Εγκέφαλος λειτουργεί συνεχώς would usually sound unnatural or incomplete in a normal statement like this. Greek normally wants the article with a noun like this, especially in a general statement.

So for a learner, the safe choice is:

• Ο εγκέφαλος λειτουργεί συνεχώς.

not

• Εγκέφαλος λειτουργεί συνεχώς.

The accent mark shows which syllable is stressed.

In this sentence:

• εγκέφαλος → stress on κέ
• λειτουργεί → stress on εί
• συνεχώς → stress on χώς

So you can think of them roughly as:

• εγ-ΚΕ-φα-λος
• λει-τουρ-γΕΙ
• συ-νε-χΩΣ

Stress matters in Greek, so the written accent is important.

λειτουργεί is:

• present tense
• active voice
• 3rd person singular

Its dictionary form is λειτουργώ, meaning I function / I operate.

Because the subject is singular (ο εγκέφαλος), the verb is also singular: λειτουργεί = functions / operates.

It can cover several of those ideas, depending on context.

In Greek, the present tense often corresponds to both:

• English simple present: functions / works
• English present progressive: is functioning / is working

In this sentence, because it states a general fact, English usually uses the simple present:

• The brain functions continuously.

But grammatically, Greek λειτουργεί is just the present tense, and context tells you how to translate it best.

Both can sometimes be translated as works, but they are not exactly the same.

λειτουργεί means something like:

• functions
• operates
• is in operation

It sounds more appropriate for:

• organs
• systems
• machines
• institutions

δουλεύει often means works too, but it can sound more everyday and is also very commonly used for working in the sense of having a job or for something functioning in a more casual way.

For the brain, λειτουργεί is a very natural and precise choice.

συνεχώς is an adverb, meaning:

• continuously
• constantly
• without stopping

It describes how the brain functions.

Because it is an adverb, it does not change to agree with the noun. It stays the same regardless of gender, number, or case.

Yes. It is related to the adjective συνεχής, which means continuous.

A useful pattern to notice is that many Greek adverbs end in -ως. So seeing συνεχώς can help you recognize that it is functioning as an adverb.

Very roughly:

• συνεχής = continuous
• συνεχώς = continuously

No, Greek word order is more flexible than English word order.

The version you have:

• Ο εγκέφαλος λειτουργεί συνεχώς.

is neutral and natural.

But Greek can move words around for emphasis, for example:

• Ο εγκέφαλος συνεχώς λειτουργεί.
• Συνεχώς λειτουργεί ο εγκέφαλος.

These are possible, but they may sound more marked or emphasize a different part of the sentence. For a learner, the original order is the best one to use.

Greek often drops subject pronouns because the verb ending already shows the person, for example:

• λειτουργώ = I function
• λειτουργεί = he/she/it functions

But here the subject is not a pronoun like it; it is a full noun phrase: ο εγκέφαλος.

So:

• Ο εγκέφαλος λειτουργεί συνεχώς. = clear and complete

If you say only:

• Λειτουργεί συνεχώς.

that means It functions continuously or He/She functions continuously, and the subject would have to be understood from context. On its own, it is less clear.

In Greek, verbs do not change for grammatical gender in forms like this.

The verb λειτουργεί only tells you things like:

• person
• number
• tense

It agrees with the subject in number and person, but not in gender.

So whether the subject were masculine, feminine, or neuter, the 3rd person singular present form would still be λειτουργεί.