Dux victoriae potis est.

Dux is nominative singular. It is the subject of the sentence: the person who is something.

It is a third-declension noun, so its nominative singular form does not end in -us or -a the way many beginners expect.

Latin has no articles. There is no separate word for the or a/an.

So dux can mean:

• the leader
• a leader

Which one is best depends on context and on the translation already given.

Here victoriae is genitive singular.

Even though victoriae could be several things in isolation:

• genitive singular
• dative singular
• nominative plural

the grammar of this sentence points to genitive singular, because potis can take a genitive complement.

Because potis does not work here like an ordinary transitive verb taking a direct object.

Instead, potis can mean having power over, capable of, or master of, and with that meaning it commonly takes the genitive.

So victoriae potis est means something like:

• is capable of victory
• is master of victory
• has command over victory

not victory as a direct object.

Potis is an adjective. Its basic idea is able, powerful, capable, or master of.

In this sentence it is a predicate adjective: it describes the subject dux, with est linking them.

So structurally the sentence is:

dux = subject
potis = adjective describing the subject
est = linking verb
victoriae = complement depending on potis

Because potis is an adjective, not a complete finite verb by itself.

Latin needs est to say is able, is capable, or is master of.

So:

• potis = able/capable
• potis est = is able / is capable

Yes. They are historically very closely related.

In fact, potest developed from potis est. That is why they look similar.

But in this sentence, potis est is being used as an adjective + est construction, and it takes victoriae in the genitive. That is a bit different from the more familiar potest from possum, which usually goes with an infinitive, as in vincere potest = he/she can conquer.

Yes. Potis agrees with dux as a predicate adjective.

Here both are singular, and potis is the form used with a masculine or feminine singular subject. Since dux can refer to a male or female leader depending on context, potis still fits.

Latin word order is much more flexible than English word order.

English usually depends heavily on position, but Latin mostly shows grammatical relationships through endings. That means the writer can move words around for style, emphasis, or rhythm.

In this sentence:

• dux comes first as the topic or subject
• victoriae is placed before potis because it belongs closely with it
• potis est comes at the end, which is a very natural Latin place for the predicate

So the order is normal Latin, even though it feels unusual in English.

It is a bit more literary or old-fashioned than the very common possum / potest construction.

A learner is much more likely to meet:

• potest
  • infinitive

than:

• potis est
  • genitive

But potis is still an important word to know, especially because it helps explain where forms like potest come from and because it appears in older, poetic, and elevated Latin styles.