Ο ήχος ήταν τρομερός.

Because ήχος is a masculine noun in Greek, so it takes the masculine singular definite article ο.

Greek definite articles change for gender, number, and case:

• ο = masculine singular nominative
• η = feminine singular nominative
• το = neuter singular nominative

So:

• ο ήχος = the sound

Even though sound is not masculine in English, Greek nouns have grammatical gender, and you simply learn each noun together with its article.

The biggest clue is the article: ο ήχος. In Greek, the article clearly shows the noun’s gender.

Also, many nouns ending in -ος are masculine, though not all of them are. So the safest habit is to learn nouns as a pair:

• ο ήχος = the sound

rather than learning ήχος by itself.

Ήχος is the noun meaning sound.

Its basic singular forms are:

• nominative: ο ήχος
• genitive: του ήχου
• accusative: τον ήχο

In this sentence, it is in the nominative because it is the subject of the sentence: the sound was terrible.

Ήταν is the past tense form of είμαι (to be).

Here it means was.

A useful thing to know: ήταν can also mean were, depending on the subject. So Greek does not always distinguish singular and plural in this form:

• Ο ήχος ήταν τρομερός. = The sound was terrible.
• Οι ήχοι ήταν τρομεροί. = The sounds were terrible.

Ήταν is the normal past form used for description, states, or background information.

In this sentence, the speaker is describing what the sound was like, so ήταν is exactly what you would expect.

It is not an action verb like happened or became. It simply links the subject to a description:

• Ο ήχος = the sound
• ήταν = was
• τρομερός = terrible / tremendous / awful, depending on context

Because it is an adjective that must agree with ήχος.

In Greek, adjectives agree with the noun they describe in:

• gender
• number
• case

Since ήχος is masculine singular nominative, the adjective must also be masculine singular nominative:

• ο ήχος ήταν τρομερός

If the noun changed, the adjective would change too:

• η μουσική ήταν τρομερή = the music was terrible / amazing
• το θέαμα ήταν τρομερό = the sight was terrible / amazing

Not always.

Τρομερός can mean something like:

• terrible
• awful
• frightening
• tremendous
• amazing
• incredible

The exact meaning depends heavily on context and tone.

So Ο ήχος ήταν τρομερός could mean:

• The sound was terrible
• The sound was tremendous / incredible

But in many straightforward learning contexts, it is often understood as something negative, such as terrible or awful.

Because here τρομερός is a predicate adjective, not an adjective directly placed before the noun.

The structure is:

• Ο ήχος = the subject
• ήταν = the linking verb
• τρομερός = the description

So this works like English:

• The sound was terrible

If you wanted the adjective directly attached to the noun, you could say something like:

• ο τρομερός ήχος = the terrible sound

That is a different structure.

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

The neutral, natural order here is:

• Ο ήχος ήταν τρομερός.

But other orders are possible for emphasis, such as:

• Τρομερός ήταν ο ήχος.
• Ήταν τρομερός ο ήχος.

These can sound more marked or emphatic depending on context. For beginners, the standard order subject + verb + adjective is the safest pattern to use.

The accent marks show which syllable is stressed when you pronounce the word.

• ήχος → stress on the first syllable: EE-hos
• τρομερός → stress on the last syllable: tro-me-ROS

Stress matters in Greek, so the written accent is important and should be learned with the word.

A simple pronunciation guide is:

O EE-hos EE-tan tro-me-ROS

A few notes:

• ο sounds like o in for or a short o
• η sounds like ee
• χ is a rough sound, like the ch in German Bach or Scottish loch
• ρ is a rolled or tapped r
• the stressed syllables are:
  • ή in ήχος
  • ρός in τρομερός

Because τρομερός is not a separate noun phrase here. It is just the adjective describing the subject after the verb ήταν.

Compare:

• Ο ήχος ήταν τρομερός. = The sound was terrible.
• Ο τρομερός ήχος = The terrible sound.

In the first sentence, τρομερός is part of the predicate, so no article is needed before it.

Yes, very closely:

• Ο = the
• ήχος = sound
• ήταν = was
• τρομερός = terrible / tremendous / amazing

So the structure is almost identical to English:

• The sound was terrible.

That makes this sentence a nice example of a very common Greek pattern: article + noun + ήταν + adjective.