Mater fenestram claudit, quia aer frigidus in cubiculum intrat.

Because fenestram is the accusative singular form of fenestra (window).

In Mater fenestram claudit, the mother is closing the window, so window is the direct object of the verb claudit. In Latin, direct objects usually go in the accusative case.

• fenestra = window as a subject
• fenestram = window as a direct object

So:

• Fenestra clauditur = The window is being closed
• Mater fenestram claudit = Mother closes the window

We know because mater is in the nominative singular, which is the case typically used for the subject of the sentence.

Also, the verb claudit is third person singular (he/she/it closes), and mater is a singular noun, so they match.

So in:

• Mater fenestram claudit

mater = the one doing the action
fenestram = the thing receiving the action

Quia means because. It introduces a clause that gives the reason for the main action.

So the sentence is divided like this:

• Mater fenestram claudit = the main statement
• quia aer frigidus in cubiculum intrat = the reason why

This is very similar to English:

• Mother closes the window because cold air enters the bedroom.

Because frigidus is an adjective describing aer, and adjectives in Latin must agree with the nouns they describe in gender, number, and case.

Here:

• aer is masculine singular nominative
• so the adjective must also be masculine singular nominative
• therefore: frigidus

If the noun were neuter, you might expect frigidum, but aer is masculine.

So:

• aer frigidus = cold air

Cubiculum is in the accusative singular here because it follows in with the idea of motion into a place.

Latin uses:

• in + accusative = into / movement toward a place
• in + ablative = in / location in a place

So:

• in cubiculum intrat = enters into the bedroom
• but in cubiculo est would mean he/she/it is in the bedroom

That is an important distinction in Latin.

Because its subject is aer, which is singular.

Intrat means enters or is entering. It is:

• third person singular
• present tense
• active voice

Since aer = air is grammatically singular in Latin, the verb is singular too.

Latin word order is more flexible than English word order because Latin uses case endings to show each word’s function.

So even if the words were rearranged, the meaning would usually stay clear, for example:

• Mater fenestram claudit
• Fenestram mater claudit

Both still mean Mother closes the window, because:

• mater is nominative
• fenestram is accusative

However, word order still matters for emphasis and style. The given order is natural and straightforward.

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

So:

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

You understand which is meant from the context.

Yes. In English, enter already contains the idea of going into, so we often translate:

• in cubiculum intrat as enters the bedroom or goes into the bedroom

Latin often uses both:

• the verb intrat = enters
• plus in + accusative = into

So the Latin is perfectly normal, even if English may not always translate every part separately.

Mater is a third-declension noun.

Its basic forms are:

• nominative singular: mater
• genitive singular: matris

That genitive form tells you it belongs to the third declension.

Learners often notice that mater looks a bit unusual because it ends in -er, but it is not a second-declension noun like puer or magister. Its genitive matris is the clue.

Claudit comes from claudere, which is a third-conjugation verb meaning to close or to shut.

Its form here is:

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

So claudit means:

• he closes
• she closes
• it closes

In this sentence:

• Mater fenestram claudit = Mother closes the window

Because the verb ending already tells you the person and number.

Claudit means he/she/it closes, so Latin does not need to add a separate pronoun unless it wants extra emphasis.

Since mater is already the subject, adding ea (she) would usually be unnecessary.

Latin often leaves subject pronouns unstated when the meaning is clear from the verb and context.