Milites arcem defendunt.

• milites = soldiers
• arcem = citadel, fortress, or stronghold
• defendunt = defend or are defending

So the sentence means The soldiers defend the citadel or The soldiers are defending the citadel.

Milites is in the nominative plural, which is the case normally used for the subject of a sentence.

Also, the verb defendunt ends in -unt, which means they. That matches a plural subject, so milites is the group doing the action.

Because arcem is the accusative singular form of arx.

The dictionary form is arx, meaning citadel. But when the word is used as the direct object of the verb, Latin changes its form:

• nominative singular: arx = the citadel as subject
• accusative singular: arcem = the citadel as direct object

Since the soldiers are defending the citadel, arcem is the thing receiving the action, so it must be accusative.

Arcem is in the accusative case because it is the direct object of defendunt.

A direct object answers the question whom? or what? after the verb:

• The soldiers defend what?
• They defend the citadel.

So Latin uses the accusative: arcem.

Defendunt is:

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

It comes from the verb defendere, meaning to defend.

So defendunt means they defend or they are defending.

Latin usually does not have definite or indefinite articles like English the or a/an.

So:

• milites can mean soldiers or the soldiers
• arcem can mean a citadel or the citadel

You figure out the most natural translation from the context. In this sentence, the soldiers defend the citadel is the most natural English rendering.

No. Latin word order is more flexible than English word order because the endings show each word's job.

So all of these could mean basically the same thing:

• Milites arcem defendunt
• Arcem milites defendunt
• Defendunt milites arcem

However, the chosen order can affect emphasis. The basic sentence here is straightforward: subject + object + verb.

Yes. The Latin present tense often covers both ideas that English separates:

• they defend
• they are defending

Latin does not always distinguish between simple present and present progressive the way English does. Context tells you which translation sounds better.

Milites comes from miles, militis, meaning soldier.

It is a third-declension noun.

Here are the key forms:

• nominative singular: miles = soldier
• nominative plural: milites = soldiers

So in this sentence, milites is nominative plural, the subject.

Arx, arcis is also a third-declension noun.

Important forms:

• nominative singular: arx
• accusative singular: arcem

That is why the sentence uses arcem rather than arx: it is the object of the verb.

In Latin, verbs agree with their subjects in person and number.

• milites = plural
• defendunt = they defend, so also plural

Because both are plural, they match correctly.

If the subject were singular, the verb would be different, for example:

• Miles arcem defendit = The soldier defends the citadel

The structure is:

• milites = subject
• arcem = direct object
• defendunt = verb

So it is a simple subject-object-verb sentence: The soldiers / the citadel / defend

In smoother English: The soldiers defend the citadel.

A common classroom pronunciation would be roughly:

mee-LEE-tays AR-kem day-FEN-doont

More exactly in reconstructed classical pronunciation:

• milites = mi-li-tēs
• arcem = ar-kem
• defendunt = de-fen-doont

The c in arcem is always hard, like k.