Τρομάζω όταν ο σκύλος γαβγίζει ξαφνικά τη νύχτα.

Because Greek usually drops subject pronouns when they are not needed. The verb ending already shows the subject.

• τρομάζω = I get startled / I am frightened
• so εγώ is understood automatically

You could say Εγώ τρομάζω..., but that would sound more emphatic, like I’m the one who gets scared.

Here τρομάζω means I get scared, I get startled, or I am frightened.

A useful detail: τρομάζω can be used in two ways:

• intransitively: I get frightened
• transitively: I frighten someone

So in this sentence it is intransitive:

• Τρομάζω όταν... = I get scared when...

But in another sentence:

• Τρομάζω το παιδί. = I scare the child.

It is also a bit more like be startled than φοβάμαι, which usually means a more general or ongoing I am afraid.

Because Greek present tense often describes habitual or repeated actions, not only what is happening right now.

So this sentence means something like:

• I get scared whenever the dog suddenly barks at night

It is not necessarily about one single moment. It describes a regular reaction.

If you wanted a single past event, you would use a past form, for example:

• Τρόμαξα όταν ο σκύλος γάβγισε... = I got scared when the dog barked...

όταν means when.

It introduces a time clause:

• όταν ο σκύλος γαβγίζει ξαφνικά τη νύχτα = when the dog suddenly barks at night

In this sentence, because the verb after it is in the present tense, the whole idea is repeated/habitual:

• when / whenever the dog barks...

So in context, όταν can feel close to whenever.

For the same reason: the sentence describes a repeated situation.

• γαβγίζει = barks / is barking
• here it means barks in the general sense: when the dog barks

It is the 3rd person singular present of γαβγίζω:

• I bark = γαβγίζω
• he/she/it barks = γαβγίζει

Since ο σκύλος is singular, γαβγίζει must also be singular.

Because ο σκύλος is the subject of γαβγίζει.

• ο σκύλος = the dog in the nominative case
• τον σκύλο would be the object in the accusative case

Here the dog is the one doing the barking, so Greek uses the nominative:

• ο σκύλος γαβγίζει = the dog barks

If the dog were receiving the action, you would use τον σκύλο.

ξαφνικά is an adverb meaning suddenly.

It modifies the verb γαβγίζει, telling us how the dog barks:

• γαβγίζει ξαφνικά = barks suddenly

Greek adverbs do not change form for gender, number, or case.

Its position is fairly flexible, although some placements sound more natural than others. For example:

• ο σκύλος γαβγίζει ξαφνικά τη νύχτα
• ο σκύλος ξαφνικά γαβγίζει τη νύχτα

The first version is more neutral.

Because Greek often uses the accusative by itself for expressions of time.

So:

• τη νύχτα = at night
• την Κυριακή = on Sunday
• το καλοκαίρι = in the summer

This is very common and natural.

If you said στη νύχτα, it would usually not mean the ordinary time expression at night. It would sound more literal, poetic, or context-specific, like into the night or in the night in a more concrete sense.

The full form of the article is την, but the final -ν is often dropped in pronunciation and writing before certain consonants.

So both may be seen, but here τη νύχτα is the normal form.

This happens with words like την and τον quite often in Modern Greek. The -ν is usually kept before:

• vowels
• κ, π, τ
• γκ, μπ, ντ
• ξ, ψ

Since νύχτα begins with ν, dropping the final -ν is common:

• τη νύχτα

Yes. Greek word order is more flexible than English.

This sentence could also be:

• Όταν ο σκύλος γαβγίζει ξαφνικά τη νύχτα, τρομάζω.

That has basically the same meaning.

The difference is mostly one of focus or style:

• Τρομάζω... puts the reaction first
• Όταν ο σκύλος... sets up the situation first

Both are natural Greek.

Greek uses the definite article more often than English does.

• ο σκύλος = the dog
• τη νύχτα = literally the night, but idiomatically at night

In ο σκύλος, the article marks the noun as definite and also shows its gender, number, and case.

In τη νύχτα, the article is part of a very common time expression. English does not use the there, but Greek normally does.