Oleum viride in dolio oleario manet.

Oleum is nominative singular, which is the case normally used for the subject of a finite verb. We know it is the subject because it matches the verb manet (remains / stays), which is third person singular: the oil remains.

Also, oleum is a neuter second-declension noun, so its nominative singular form ends in -um.

Because viride must agree with oleum.

The adjective viridis, viride is a third-declension adjective meaning green. Since oleum is:

• singular
• nominative
• neuter

the adjective has to be singular, nominative, and neuter too. The nominative singular neuter form of this adjective is viride.

So:

• viridis = masculine/feminine nominative singular
• viridem = masculine/feminine accusative singular
• viride = neuter nominative singular

Dolio oleario is ablative singular.

That is because the preposition in takes the ablative when it means in / on / inside in the sense of location. Here the oil is already in the jar, so this is a location phrase, not motion toward something.

So:

• in dolio oleario = in the oil jar
• if it meant motion into the jar, Latin would normally use in
  • accusative instead

By form alone, dolio could be either dative singular or ablative singular. But the preposition in tells you what it is here.

After in, when the meaning is location, Latin uses the ablative. So in this sentence dolio must be ablative, not dative.

The same is true for oleario, which agrees with dolio and is also ablative singular.

Oleario is an adjective from olearius, -a, -um, meaning connected with oil or for oil.

So dolium olearium is literally an oil jar, oil cask, or jar for oil. It describes what kind of jar it is.

This is a very common Latin pattern: a noun is modified by an adjective that shows purpose, material, association, or type.

Manet is:

• present tense
• active voice
• indicative mood
• third person singular

It comes from manere, meaning to remain, to stay, or to continue to be.

It is singular because its subject, oleum, is singular.

Manet is more specific than est.

• est means is
• manet means remains or stays

So the sentence is not just saying that the oil exists in the jar. It says that the oil remains there or stays there.

Latin word order is much freer than English word order because the endings show the grammar. Putting the verb at the end is very common in Latin, especially in straightforward prose.

So Oleum viride in dolio oleario manet is a very natural Latin order:

• subject first
• description of the subject
• prepositional phrase
• verb last

But other orders are also possible, for example:

• In dolio oleario oleum viride manet
• Oleum in dolio oleario viride manet

The basic meaning stays the same, though the emphasis may change.

In Latin, adjectives can come either before or after the noun. Unlike in English, the position is more flexible.

So both of these are possible:

• oleum viride
• viride oleum

Putting the adjective after the noun is very common and often feels neutral. If the adjective is placed before the noun, it can sometimes give it a little more emphasis, but the exact effect depends on context and style.

Often, yes. In many Latin contexts, oleum naturally refers to olive oil, because that was the most common kind of oil in everyday Roman life.

But the word itself basically means oil, and the exact nuance depends on context. In a simple learning sentence like this, it is safest to understand oleum as oil, unless the broader context clearly points to olive oil.

Not in this sentence.

With in:

• in
  • ablative = location, in / inside
• in
  • accusative = motion toward, into

Since we have dolio oleario in the ablative, the phrase means in the oil jar, not into the oil jar.

So this sentence describes where the oil is, not movement into that place.