Rex in monte altissimo stat.

Rex is nominative singular, the case normally used for the subject of the sentence.

The basic dictionary form is rēx, meaning king. In this sentence, the king is the one doing the action of stat, so nominative is exactly what we expect.

Because mons is the dictionary form or nominative singular, but after the preposition in here, the noun must be in the ablative case.

So:

• mons = mountain, as a subject
• monte = on/in a mountain, after in with location

This noun belongs to the 3rd declension:

• nominative: mons
• genitive: montis
• ablative: monte

So in monte means on the mountain or in the mountain, depending on context. In this sentence, English usually says on the mountain.

Latin in can take two different cases, depending on the meaning:

• in + ablative = in/on a place, showing location
• in + accusative = into/onto a place, showing motion toward

Here the king is not moving onto the mountain; he is already there, standing there. So Latin uses:

• in monte altissimo = on the very high / highest mountain

If the sentence were about motion, you would expect accusative instead, for example something like in montem.

Altissimo is the form of the adjective altissimus, which is the superlative of altus.

So:

• altus = high
• altior = higher
• altissimus = highest / very high

In this sentence, altissimo is ablative singular masculine, because it must agree with monte, which is also ablative singular masculine.

So the ending changes to match the noun it describes.

It can mean either, depending on context.

Latin superlatives often have two possible senses:

• the highest
• very high

So in monte altissimo could be understood as:

• on the highest mountain
• on a very high mountain

If there is no wider context, both are grammatically possible. Often a teacher or translation chooses one based on what sounds most natural.

Because Latin adjectives must agree with the nouns they describe in:

• gender
• number
• case

Here:

• monte = masculine, singular, ablative
• altissimo = masculine, singular, ablative

They match because altissimo describes monte.

This is one of the most important patterns in Latin: adjectives change their endings to fit the noun.

Latin word order is much more flexible than English word order because the endings already show the grammatical relationships.

English depends heavily on position:

• The king stands on the mountain

Latin can move words around more freely:

• Rex in monte altissimo stat
• In monte altissimo rex stat
• Stat rex in monte altissimo

All of these can mean basically the same thing, though the emphasis may change.

In your sentence, putting rex first gives it some prominence, and placing stat at the end is very common Latin style.

Stat is from the verb stare, meaning to stand.

So stat means:

• he stands
• he is standing

It is 3rd person singular present active indicative.

It does not simply mean is. Latin uses stat when the idea of standing upright or being stationed matters.

So this sentence is more vivid than just saying the king is on the mountain.

Latin has no articles like English the and a/an.

So rex can mean:

• the king
• a king

And monte altissimo can mean:

• the very high mountain
• a very high mountain
• the highest mountain

The context tells you which one is meant. When translating into English, you have to choose the article that sounds best.

Yes. Latin in often covers both English in and on, depending on the situation.

So:

• in urbe = in the city
• in horto = in the garden
• in monte = on the mountain

English chooses the preposition that sounds natural, but Latin still uses in.

Yes. Depending on how you take altissimo and how natural your English is, you might translate it as:

• The king is standing on the very high mountain.
• The king stands on the very high mountain.
• The king stands on the highest mountain.
• A king stands on a very high mountain.

The grammar stays the same; the differences come from:

• Latin having no articles
• the superlative altissimus allowing more than one nuance
• English style choices such as stands vs is standing

A common restored classical pronunciation would be roughly:

Rēks in monte altissimō stat

A very approximate English-style guide is:

rakes in MON-te al-TIS-si-mo staht

A few helpful points:

• x in rex sounds like ks
• e is always a clear vowel, not silent
• ti in altissimo is a normal ti, not sh
• a in stat is like a in father

If you are focusing on grammar first, pronunciation does not change the analysis of the sentence, but it is useful to know.