Mater non sinit puellam extra ostium currere, quia pluvia cadit.

Because puellam is the object of sinit.

The verb sinere means to allow, to let, and in Latin it often takes:

• a person in the accusative
• plus an infinitive

So:

• Mater = the mother
• non sinit = does not allow
• puellam = the girl
• currere = to run

Literally, the structure is something like:

The mother does not allow the girl to run.

That is why puellam is accusative.

Because after sinit, Latin normally uses an infinitive to say what someone is allowed or not allowed to do.

So:

• sinit puellam currere = allows the girl to run
• non sinit puellam currere = does not allow the girl to run

This is a very common Latin pattern:

verb of ordering / allowing / wanting + accusative person + infinitive

In English we often translate it with to:

• to run

But Latin does not use a separate word for to here. The infinitive ending itself already carries that meaning.

In this construction, the accusative noun before the infinitive is understood as the subject of the infinitive.

So in:

Mater non sinit puellam ... currere

the one who runs is puellam.

A good way to see it is:

• Mater = main subject of sinit
• puellam = object of sinit, but also the understood subject of currere

So the sentence means:

The mother does not allow the girl to run...

not:

The mother does not allow someone to run the girl.

Extra means outside or beyond, and it takes the accusative case.

So:

• extra = outside/beyond
• ostium = door, doorway, entrance
• extra ostium = outside the door / beyond the doorway

That is why ostium is accusative here.

A native English speaker may expect outside the door to work like a normal prepositional phrase, and in Latin it does, but you must remember that extra specifically governs the accusative.

Both words can be connected with the idea of a door, but they are not always exactly the same.

• ianua often means the door itself or the entrance of a house
• ostium often means doorway, entrance, opening

In many beginner sentences, ostium can be translated simply as door, but the sense may be closer to doorway or entrance.

So extra ostium currere suggests running outside the doorway / out past the entrance.

Because non normally negates the word or phrase that follows, and here it negates the verb sinit:

• sinit = allows
• non sinit = does not allow

This is the most straightforward and common placement.

Latin word order is flexible, but non often comes directly before the word it negates, especially the verb.

Quia means because and introduces a reason.

So the sentence has:

• a main clause: Mater non sinit puellam extra ostium currere
• a reason clause: quia pluvia cadit

Together:

The mother does not allow the girl to run outside the door, because it is raining.

For an English speaker, this works very much like because.

Because that is a normal Latin way to express it is raining or rain is falling.

• pluvia = rain
• cadit = falls

Latin often uses very concrete verbs where English may prefer an impersonal expression like it is raining.

So even though the literal wording is rain falls, the natural meaning is simply:

it is raining

Because Latin does not need a dummy subject like English it in weather expressions.

In English we say:

• it is raining

But the it does not really refer to anything.

Latin can simply say:

• pluvia cadit = rain falls

So the sentence does not need any equivalent of English it.

Latin often places the verb near the end of a clause, especially in simple prose. So:

• quia pluvia cadit

is a very normal Latin order.

English word order is much more fixed, but Latin is more flexible because the endings show each word’s role.

You could think of this clause as:

• quia = because
• pluvia = rain
• cadit = falls

The final verb is completely natural in Latin.

It can mean either, depending on context, because Latin has no articles.

So mater could be:

• a mother
• the mother
• sometimes even mother in a more general sense

In this sentence, English usually translates it as the mother because the context probably refers to a specific mother and girl.

They are both present tense because the sentence describes what is happening now or what is true at the moment:

• sinit = allows / is allowing
• cadit = falls / is falling

Latin present tense can often be translated in more than one way in English:

• does not allow
• is not allowing

and

• rain falls
• is raining
• is falling

English chooses the most natural translation from context.

Their dictionary forms are:

• sinit → sinere = to allow, to let
• currere → currere = to run

A learner may notice that currere already looks like a dictionary form. That is because dictionary entries for verbs are usually given in the infinitive, and currere here is also an infinitive in the sentence.

Sinit, however, is a finite verb form, specifically third person singular present:

• he/she/it allows
• here: the mother allows

With non, it becomes:

• does not allow

Yes. Latin often has more than one natural way to express an idea.

For example, instead of extra ostium, another expression of going outside might appear in other contexts. Also, a different verb for forbidding could be used, depending on style and level.

But for this sentence, non sinit + accusative + infinitive is a very standard and useful pattern to learn:

Mater non sinit puellam currere.
= The mother does not allow the girl to run.

So this sentence is a good model for an important Latin construction.