Mater fenestram claudit, ne culices in cubiculum intrent.

Because fenestram is the direct object of claudit: it is the thing being closed.

• fenestra = window as a subject form, nominative singular
• fenestram = window as a direct object, accusative singular

So Mater fenestram claudit means Mother closes the window, where mother is doing the action and window receives it.

Because mater is the subject of the sentence, so it stays in the nominative case.

• mater = nominative singular, mother as subject
• matrem = accusative singular, mother as object

Here, mother is the one doing the closing, so Latin uses mater.

Claudit is from claudere, meaning to close or to shut.

Here it is:

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

So claudit means she closes or is closing. Since the subject is mater, we understand it as mother closes.

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

So:

• mater can mean mother, a mother, or the mother
• fenestram can mean a window or the window
• cubiculum can mean a bedroom or the bedroom

You figure out the most natural English wording from the context.

Here ne introduces a negative purpose clause. It means:

• so that ... not
• or more naturally in English, lest

So:

• ne culices in cubiculum intrent = so that mosquitoes do not enter the bedroom

This is a very common Latin construction:

• ut = so that
• ne = so that ... not

Because after ne in a purpose clause, Latin normally uses the subjunctive.

So:

• intrant = they enter / are entering in the indicative
• intrent = they may enter / might enter in the subjunctive

In this sentence, the mother closes the window for the purpose of preventing something, so Latin uses the subjunctive:

• ne ... intrent = so that ... may not enter

Culices is the subject of intrent.

The clause means:

• culices intrent = the mosquitoes enter

So the mosquitoes are the ones doing the entering.

A learner may wonder because culices can look ambiguous, but here the verb intrent is plural, and the meaning makes it clear that culices is the subject of the subordinate clause.

Because in takes different cases depending on whether it shows motion or location.

• in + accusative = into, motion toward
• in + ablative = in/on, location

So:

• in cubiculum = into the bedroom
• in cubiculo = in the bedroom

Since the mosquitoes would be entering into the bedroom, Latin uses the accusative: cubiculum.

Latin word order is much more flexible than English word order. Verbs, especially in subordinate clauses, often come near the end.

So ne culices in cubiculum intrent is a very natural Latin order.

The sentence is arranged in a way that many Latin writers like:

• main statement first: Mater fenestram claudit
• purpose clause after it: ne culices in cubiculum intrent

English depends heavily on word order for grammar, but Latin uses endings much more, so the order can be freer.

Normally, no. For a negative purpose clause, classical Latin usually uses ne, not ut non.

So:

• ut intrent = so that they may enter
• ne intrent = so that they may not enter

Using ut non here would generally not be the standard classical way to express simple negative purpose.

A very literal breakdown is:

• ne = so that not
• culices = mosquitoes
• in cubiculum = into the bedroom
• intrent = may enter

So, literally: so that mosquitoes may not enter into the bedroom

More natural English would be: so that mosquitoes do not enter the bedroom or to keep mosquitoes from entering the bedroom