Ο υπαίτιος πράγματι υπέγραψε.

Ο is the masculine singular nominative form of the definite article, so it means the.

In this sentence, it goes with υπαίτιος, so Ο υπαίτιος means something like:

• the culprit
• the person responsible
• the guilty party

Greek articles change for gender, number, and case, unlike English the, which always stays the same.

Grammatically, υπαίτιος is originally an adjective, meaning responsible, guilty, or at fault.

But here it is being used substantively, meaning it functions like a noun. So:

• ο υπαίτιος = the guilty one
• more naturally in English: the culprit / the one responsible

This is very common in Greek: an adjective with the article can act like a noun.

πράγματι is an adverb meaning:

• indeed
• in fact
• actually
• really (in some contexts)

In this sentence, it confirms that the action truly happened:

• Ο υπαίτιος πράγματι υπέγραψε.
• The culprit did indeed sign.

It is a slightly more formal or literary-sounding word than some other everyday options.

Greek word order is fairly flexible, especially with adverbs.

Here, πράγματι comes after the subject and before the verb:

• Ο υπαίτιος πράγματι υπέγραψε.

That placement emphasizes the truth of the action: the culprit really did sign.

You may also see adverbs in other positions depending on emphasis. Greek often uses word order to highlight what is important, rather than following a rigid pattern like English.

υπέγραψε is the aorist form, specifically:

• third person singular
• active
• indicative

It comes from υπογράφω = I sign

So υπέγραψε means:

• he/she/it signed

In this sentence, since the subject is ο υπαίτιος, it means:

• the culprit signed

The Greek aorist usually presents the action as a complete event.

This is because the verb has an irregular aorist stem.

The base verb is:

• υπογράφω = I sign

Its aorist is built from the same pattern as γράφω → έγραψα:

• γράφω → έγραψα
• υπογράφω → υπέγραψα

Then the 3rd person singular is:

• υπέγραψε = he/she signed

A few things are happening:

• the prefix υπο- becomes υπ- before the rest of the form
• the past marker appears after the prefix
• the stem changes to -γραψ-, as in the aorist of γράφω

So this is a form you mostly need to learn as part of the verb’s principal parts.

A rough pronunciation guide is:

• Ο = o
• υπαίτιος = ee-PAI-tee-os
• πράγματι = PRAG-ma-ti
• υπέγραψε = ee-PE-gra-pse

A few useful notes:

• αι sounds like e in Modern Greek, so υπαίτιος is not pronounced the way the spelling might suggest to an English speaker.
• γρ in πράγματι and υπέγραψε is pronounced smoothly together.
• ψ in υπέγραψε sounds like ps.

The stress falls where the accent marks are:

• υπαίτιος
• πράγματι
• υπέγραψε

By itself, υπέγραψε can mean:

• he signed
• she signed
• sometimes it signed, depending on context

Greek verbs in the third person singular do not show natural gender.

Here, the subject ο υπαίτιος is grammatically masculine, so the sentence refers to a male culprit, or at least uses the masculine form.

If the subject were feminine, you might see:

• Η υπαίτια πράγματι υπέγραψε.

The verb υπέγραψε would stay the same.

Greek often leaves out information that is already understood from context.

So υπέγραψε can stand alone as signed, even if the thing signed is not explicitly mentioned. In English we also sometimes do this:

• He signed.
• She finally signed.

The object might be obvious from the surrounding context, such as:

• a document
• a contract
• a confession
• a statement

So the sentence does not need to mention it.

Yes. Depending on tone and nuance, Greek has other adverbs that can express a similar idea, such as:

• όντως = really / indeed
• αλήθεια in some contexts = really / truly
• στην πραγματικότητα = in reality / actually (less suitable here)

But πράγματι has a specific flavor: it sounds like indeed / in fact, and it can feel a bit formal or written.

So in this sentence, πράγματι is a good choice if the speaker is confirming something.

It sounds fairly neutral to slightly formal, mainly because of πράγματι and the word υπαίτιος.

• υπαίτιος is not the most casual everyday way to say culprit
• πράγματι sounds more formal than very conversational equivalents

So the sentence would fit well in:

• reporting
• official statements
• written narration
• legal or serious contexts

In casual speech, a Greek speaker might choose simpler or more conversational wording depending on the situation.