Cum hospes in atrium intrat, canis in limine sedet.

Cum can mean different things depending on how it is used.

Here it introduces a clause with a verb:

• Cum hospes in atrium intrat = when the guest enters the atrium

So this is cum as a conjunction meaning when.

By contrast, cum can also be a preposition meaning with, but then it is followed by a noun in the ablative, for example:

• cum amico = with a friend

So the structure tells you which meaning is intended:

• cum + noun = usually with
• cum + verb clause = often when, since, or although

Yes, exactly—and because hospes is the subject, it is in the nominative, not the accusative.

In Cum hospes in atrium intrat:

• hospes = the guest = subject
• intrat = enters

The accusative is usually used for a direct object, but intrat here does not take hospes as an object. The guest is the one performing the action.

So:

• hospes = nominative singular
• not accusative

This can feel unfamiliar to English speakers because English word order does more of the work, while Latin uses endings.

This is one of the most important uses of in in Latin.

With in, the case depends on the meaning:

• in + accusative = movement into or onto
• in + ablative = location in or on

So here:

• in atrium intrat = enters into the atrium

  • movement toward a place
  • therefore atrium is accusative

• in limine sedet = sits on/in the threshold

  • location at a place
  • therefore limine is ablative

This is a very common contrast in Latin.

Because not every accusative in Latin is a direct object.

In in atrium, the accusative is used because the preposition in expresses motion toward a place.

So atrium is not the object of intrat in the ordinary sense. It is the object of the preposition in, and the accusative case shows direction:

• in atrium = into the atrium

That is different from a sentence like:

• hospes canem videt = the guest sees the dog

  There, canem is a true direct object.

Limine is the ablative singular of limen, which means threshold or doorway.

Its basic forms are:

• nominative: limen
• genitive: liminis

Because it is a third-declension noun, its ablative singular ends in -e:

• limine = on the threshold / at the threshold

That is why the sentence says in limine sedet.

Because classical Latin does not have articles like English the and a/an.

So:

• hospes can mean a guest or the guest
• canis can mean a dog or the dog
• atrium can mean an atrium or the atrium

The exact sense depends on context.

English must choose an article, but Latin usually leaves that unstated unless something else makes it clear.

Latin word order is much more flexible than English word order because Latin endings show each word’s grammatical role.

English relies heavily on order:

• The dog bites the guest is different from
• The guest bites the dog

Latin can move words around more freely because forms like hospes, canis, atrium, and limine help show how they function.

In your sentence:

• Cum hospes in atrium intrat, canis in limine sedet.

the verbs come at the end of each clause, which is very common in Latin, but not required.

A Latin speaker could rearrange the words for emphasis without changing the basic meaning much.

It is in the present tense, but that does not always mean right now at this exact moment.

Latin often uses the present tense for:

• general statements
• repeated actions
• vivid narration

So this sentence can mean something like:

• When the guest enters the atrium, the dog sits on the threshold
• or more naturally in English, Whenever the guest enters the atrium, the dog sits on the threshold

It may describe a typical situation rather than one single event.

Because this is a straightforward temporal clause: when the guest enters...

When cum simply means when and gives the time of an action, Latin often uses the indicative, especially in simpler sentences like this one.

So:

• cum ... intrat = simple when clause with indicative

The subjunctive is more common with cum when the meaning is:

• since
• although
• or a more literary/background kind of when

A beginner should first recognize that this sentence uses the simple temporal pattern.

Here are the nouns in the sentence:

• hospes, hospitis = guest

  • third declension
  • here: nominative singular

• atrium, atrii = atrium, hall

  • second declension, neuter
  • here: accusative singular

• canis, canis = dog

  • third declension
  • here: nominative singular

• limen, liminis = threshold

  • third declension, neuter
  • here: ablative singular (limine)

Knowing the dictionary form helps explain why the endings look different.

Canis can be masculine or feminine depending on the sex of the dog, and sometimes the context does not make that important.

In this sentence, canis simply means dog, and nothing in the sentence forces us to decide whether it is male or female.

So an English translation may just say the dog.

Both ideas are helpful.

Intrat comes from intrare, meaning to enter. In English, enter already includes the idea of going into a place.

So:

• intrat = enters
• in atrium intrat = literally something like enters into the atrium

Latin often uses in + accusative with verbs of motion, even when the verb itself already suggests entering.

So for a learner, it is fine to understand:

• in atrium intrat = he/she enters the atrium

Yes. English may translate in limine in slightly different ways depending on context:

• at the threshold
• on the threshold
• sometimes even in the doorway

The important grammatical point is that it indicates location, not motion.

So the exact English wording may vary, but the Latin structure stays the same:

• in + ablative = being in or at a place