Ο άξονας είναι δυνατός.

Ο is the masculine singular definite article in the nominative case. In English, it usually corresponds to the.

Here, Ο άξονας means the axle / the axis.

Greek articles change depending on:

• gender: masculine, feminine, neuter
• number: singular or plural
• case: nominative, genitive, accusative, vocative

So Ο tells you that άξονας is:

• masculine
• singular
• the subject of the sentence

In Greek, every noun has a grammatical gender. Άξονας is simply a masculine noun.

That does not necessarily mean it refers to something biologically male. Grammatical gender is just part of how the noun behaves in the language.

Because άξονας is masculine, words that go with it must match that gender, including:

• the article: ο
• the adjective: δυνατός

So:

• ο άξονας
• δυνατός

all match in masculine singular nominative.

Άξονας is in the nominative singular.

You can tell because:

1. it is the subject of the sentence
2. it appears with the nominative article ο
3. the adjective δυνατός also agrees with it in the nominative

In a sentence like this:

• Ο άξονας = subject
• είναι δυνατός = predicate

So the structure is basically:

• The axle/axis
  • is
    • strong

Because adjectives in Greek must agree with the noun they describe.

Since άξονας is:

• masculine
• singular
• nominative

the adjective must also be:

• masculine
• singular
• nominative

That gives you δυνατός.

Compare:

• ο άξονας είναι δυνατός = masculine
• η μηχανή είναι δυνατή = feminine
• το υλικό είναι δυνατό = neuter

So the ending -ός shows the adjective is matching a masculine singular nominative noun.

Because here δυνατός is a predicate adjective, not an adjective directly attached inside the noun phrase.

In other words, the sentence is built like:

• The axle is strong

not:

• the strong axle

So:

• Ο άξονας είναι δυνατός = The axle is strong

If you wanted the strong axle, you would normally say:

• ο δυνατός άξονας

That is the difference between:

• attributive adjective: directly describing the noun inside the noun phrase
• predicate adjective: linked to the noun by είναι

Είναι is the third person singular form of the verb είμαι, which means to be.

Here it means is.

So:

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

In this sentence:

• Ο άξονας είναι δυνατός = The axle/axis is strong

A useful thing to remember is that είναι is the same form for:

• he is
• she is
• it is

Greek does not change this form depending on whether the subject is masculine, feminine, or neuter.

A helpful approximate pronunciation is:

AH-kso-nas

More specifically:

• ά = stressed a
• ξ = ks
• ο = short o
• νας = nas

So the stress falls on the first syllable:

• Á-xo-nas

The letter ξ is very common in Greek and is always pronounced like ks in English box.

A useful approximation is:

thee-na-TOS
or in modern Greek pronunciation more accurately: dhee-na-TOS

Notes:

• δ in Modern Greek is like the th in this, not the d in dog
• υ here sounds like ee
• the stress is on the final syllable: -τός

So:

• δυ = dhee
• να = na
• τός = TOS

Pronounced together:

• dhee-na-TOS

The accent mark in Greek shows which syllable is stressed.

In this sentence:

• άξονας → stress on the first syllable
• είναι → stress on the first part
• δυνατός → stress on the last syllable

Stress matters in Greek pronunciation, and it is normally written, unlike in English.

So the accents help you say the words correctly:

• Áxonas
• Eínai
• dynatÓS

Even when you already know the meaning, the accent marks are important for speaking and reading correctly.

Yes, Greek word order is more flexible than English word order, because endings and articles give more grammatical information.

The normal, neutral order here is:

• Ο άξονας είναι δυνατός.

But other orders may be possible for emphasis, for example:

• Δυνατός είναι ο άξονας.
• Είναι δυνατός ο άξονας.

These can sound more marked or emphatic depending on context.

For a learner, the safest default is:

• subject + είναι + adjective

So Ο άξονας είναι δυνατός is the best standard model to follow.

Sometimes Greek can omit the article, but in a sentence like this, ο άξονας is the most natural way to say the axle / the axis.

If you say just:

• Άξονας είναι δυνατός

that sounds unusual on its own and would usually need a special context.

Greek uses the definite article very often, often more than English learners expect. So if you mean the axle/axis, it is natural to include:

• ο

Not always. Δυνατός can have several related meanings depending on context, such as:

• strong
• powerful
• loud
• capable
• sometimes even intense

In this sentence, because the subject is άξονας, the most natural meaning is strong or sturdy.

So the exact English translation depends on what kind of thing is being described, but grammatically the adjective is the same.

It can mean either, depending on context.

Common meanings include:

• axis
• axle
• sometimes a figurative axis as in politics or geometry

So if this sentence appears in a mechanical context, axle may be best:

• The axle is strong.

If it appears in a mathematical or geometric context, axis may be better:

• The axis is strong would be less common in English, so context really matters.

This is a good reminder that Greek words do not always match one single English word exactly.

The sentence follows a very common Greek pattern:

article + noun + form of είμαι + adjective

So here:

• Ο = the
• άξονας = axle/axis
• είναι = is
• δυνατός = strong

This makes:

Ο άξονας είναι δυνατός.
= The axle/axis is strong.

This pattern is extremely useful and can be reused with many nouns and adjectives, for example:

• Ο τοίχος είναι ψηλός. = The wall is tall.
• Η πόρτα είναι ανοιχτή. = The door is open.
• Το σπίτι είναι μεγάλο. = The house is big.

So this sentence is a very good model for learning basic Greek sentence structure.