Amici vicissim ludunt.

Here amici is nominative plural, so it is the subject of the sentence: friends.

A beginner might notice that amici can also be genitive singular and mean of a friend. That is true in some contexts. But in this sentence, the verb ludunt is plural, so Latin expects a plural subject. That makes amici = friends the natural reading.

With macrons, the form is amīcī.

Ludunt is a verb from ludere, meaning to play.

Its grammatical features are:

• 3rd person plural
• present tense
• active voice
• indicative mood

So it means they play or they are playing, depending on context.

Because the verb is plural, it matches the plural subject amici.

Vicissim is an adverb. It describes how they play.

Its basic sense is something like:

• in turn
• one after another
• alternately
• sometimes by turns

So the sentence is not just saying that the friends play, but that they do so taking turns or alternating.

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

In English, we usually need a fairly fixed order, but in Latin the endings often show the grammatical relationships, so words can move around more freely. Here:

• amici = the subject
• ludunt = the verb
• vicissim = an adverb modifying the verb

Putting vicissim before ludunt is a natural way to highlight the manner of the action: the friends are playing in turn.

Latin could rearrange these words without changing the basic meaning very much, for example:

• Vicissim amici ludunt
• Ludunt amici vicissim

The emphasis would shift a little, but the core sense would stay similar.

Classical Latin does not have a definite article like English the, and it also does not have an indefinite article like a or an.

So amici can mean:

• friends
• the friends

Which one you choose in translation depends on the context.

In a short isolated sentence like this, English often adds the because it sounds more natural: The friends play in turn. But the Latin itself does not separately say the.

Yes. Here ludunt is used intransitively, meaning simply they play.

Latin ludere can often be used this way, just like English play can be used by itself:

• The children are playing
• Pueri ludunt

So this sentence does not need to say what they are playing. The focus is just on the action itself, especially the fact that they do it vicissim.

You would change both the noun and the verb to singular:

• Amicus vicissim ludit

That means A friend plays in turn or The friend plays in turn.

The changes are:

• amici → amicus for a singular subject
• ludunt → ludit for he/she plays

In a restored Classical pronunciation, it would sound roughly like this:

• ah-MEE-kee wik-ISS-sim LOO-doont

A few helpful points:

• c in amici is always hard, like k
• v in Classical Latin is pronounced like English w
• u is pronounced like oo
• the stress falls on:
  • amīcī → on mī
  • vicissim → on cis
  • lūdunt → on lū

So a more careful version is:

• ah-MEE-kee wi-KISS-sim LOO-doont

Not here. In this sentence amici is the noun friends.

English speakers sometimes expect a word that looks like amic- to mean friendly, because of words like amicable. But Latin amicus is primarily a noun meaning friend, though it can also be an adjective meaning friendly in some contexts.

Here the plural verb ludunt strongly supports reading amici as friends, the subject of the sentence.