Pavimentum purgatum iam siccum est.

A simple breakdown is:

• pavimentum — a noun, neuter singular
• purgatum — a perfect passive participle used adjectivally, agreeing with pavimentum
• iam — an adverb meaning now / by now / already
• siccum — an adjective, also agreeing with pavimentum
• est — the verb is

So the structure is basically:

[subject] + [describing word] + [adverb] + [describing word] + [is]

Latin often uses sum (to be) with adjectives and participles this way.

Because they all match in gender, number, and case.

Here, pavimentum is:

• neuter
• singular
• nominative

Both purgatum and siccum describe pavimentum, so they must agree with it. That is why they are also:

• neuter
• singular
• nominative

This kind of matching is called agreement.

It is a verb form used like an adjective.

More specifically, purgatum is the perfect passive participle of purgo (to clean). It means something like:

• cleaned
• having been cleaned

In this sentence, it describes pavimentum, so it works adjectivally:

• pavimentum purgatum = the cleaned floor

A participle is useful because it keeps some verbal meaning while behaving like an adjective.

Yes, they both describe pavimentum, but they describe it in different ways.

• purgatum tells you about a completed action: the floor has been cleaned
• siccum tells you its present condition: the floor is dry

So the sentence combines:

• a past-result idea: cleaned
• a current state: dry

That is why the sentence feels like The cleaned floor is now dry or The floor, once cleaned, is now dry.

The form pavimentum could be either nominative singular or accusative singular, because many second-declension neuter nouns have the same form for both.

You can tell it is nominative here because it is the subject of est:

• pavimentum ... est = the floor ... is

Also, siccum is a predicate adjective agreeing with the subject, which supports the nominative reading.

So even though the form itself is ambiguous in isolation, the sentence structure makes its function clear.

Classical Latin does not have a definite article like English the or an indefinite article like a/an.

So:

• pavimentum can mean floor, a floor, or the floor

The context tells you which one is natural in translation.

That is very normal in Latin. Learners often need to resist the urge to look for a separate word meaning the every time.

Iam often means:

• now
• already
• by now

In this sentence, it adds the idea that the floor has reached a new state:

• iam siccum est = is now dry / is already dry

So iam marks a change or a result that has been achieved.

Latin word order is much freer than English word order because Latin uses endings, not position alone, to show grammatical relationships.

Putting est at the end is very natural in Latin. In fact, forms of sum are often postponed.

So:

• Pavimentum purgatum iam siccum est

is perfectly normal.

Latin could also rearrange the sentence in other ways, for example for emphasis, though some orders would sound more natural than others.

Yes. Depending on how smoothly you want the English to sound, you could translate it in several reasonable ways, such as:

• The cleaned floor is now dry.
• The floor, having been cleaned, is now dry.
• The floor that has been cleaned is now dry.
• The floor is now dry after being cleaned.

The Latin grammar stays the same, but English offers different ways to express the participle naturally.

Grammatically, siccum goes with pavimentum.

Both purgatum and siccum independently agree with pavimentum:

• pavimentum — subject noun
• purgatum — describing the noun
• siccum — also describing the noun

So the sense is not the cleaned dry thing, where one adjective modifies the other. Instead, both words describe the same noun:

• the floor
• cleaned
• dry

Because purgatum est by itself would normally mean it has been cleaned, using the participle with est to form a perfect passive verb.

But that is not what is happening here. In this sentence:

• purgatum describes pavimentum
• siccum is the main predicate adjective
• est links the subject to siccum

So the sentence is not mainly saying the floor has been cleaned. It is saying that the floor is dry now, while also describing it as cleaned.

Yes. A very common way to unpack a Latin participle in English is with a relative clause.

So:

• pavimentum purgatum can become
• the floor that has been cleaned

That is often helpful for learners, because English does not always use participles in exactly the same way Latin does.

So one expanded reading of the whole sentence is:

• The floor that has been cleaned is now dry.