Porta infera clausa est.

A beginner-friendly breakdown is:

• porta: a noun, nominative singular feminine
  It is the subject of the sentence.

• infera: an adjective, nominative singular feminine
  It describes porta.

• clausa: a participle used adjectivally, also nominative singular feminine
  It also describes porta.

• est: the verb is, from sum, esse

So the structure is basically:

[subject] + [adjective] + [predicate adjective / participle] + [is]

Everything feminine singular agrees with porta.

Because they both agree with porta.

Since porta is:

• feminine
• singular
• nominative

the words describing it must also be:

• feminine
• singular
• nominative

So:

• porta = feminine singular nominative
• infera = feminine singular nominative
• clausa = feminine singular nominative

This agreement is very important in Latin, because it helps show which words belong together.

Infera is the feminine form of inferus, which means things like:

• lower
• below
• situated underneath

With porta, it means the lower door/gate.

A native English speaker may expect something more like inferior, but Latin often uses inferus and its forms in places where English uses lower.

Yes.

They are historically related:

• inferior comes from Latin words meaning lower
• infernal is connected with the idea of what is below, especially the lower world or underworld

So seeing infera can help you remember the basic idea of low / lower / below.

But in this sentence, it simply describes the position of the porta. It does not automatically mean anything dramatic like hellish.

Clausa is the perfect passive participle of claudere, meaning to close.

Its principal parts are:

• claudo
• claudere
• clausi
• clausum

The participle clausa literally means closed and agrees with porta.

So clausa works much like an adjective here:

• a closed gate
• the gate is closed

Latin often forms this idea with:

• a participle
  • a form of sum

So:

• clausa = closed
• est = is

Together: clausa est

This is very normal Latin.

English does the same kind of thing:

• the door is closed

So even though clausa already contains the idea of closed, you still need est to complete the statement.

This is a very common question, because Latin can be a little broader here than English.

Grammatically, clausa est can be understood as a perfect passive form, which may be translated as:

• was closed
• has been closed

But in many contexts it can also describe the resulting state very naturally as:

• is closed

So the exact English wording depends on context.

In a simple sentence like this, English learners are often shown is closed, because that sounds most natural if the point is the current condition of the door or gate.

Latin word order is much freer than English word order.

English strongly prefers:

• the lower gate
• the closed gate

Latin can put adjectives before or after the noun, and both are common.

So porta infera is perfectly normal.
Likewise, clausa can stand after porta as well.

Latin uses endings more than position to show grammar, so the sentence does not rely on fixed English-style word order.

Yes, very often.

Because the endings show the grammar, Latin can move words around for style, emphasis, or rhythm.

For example, forms like these could still be understandable in context:

• Infera porta clausa est
• Clausa est porta infera

The basic meaning stays the same, though the emphasis may shift.

The version Porta infera clausa est is straightforward and clear.

Latin has no articles.

That means there is no separate word exactly matching English the or a/an.

So porta can mean, depending on context:

• a gate
• the gate
• a door
• the door

You have to decide from context which English article sounds right.

That is why Latin sentences can look shorter than their English translations.

It can mean either, depending on context.

Common possibilities include:

• door
• gate
• entrance

In many Latin texts, porta often suggests a gate, especially a city gate or large entrance. But in simpler learning sentences, door may also be a perfectly reasonable translation.

So the right English choice depends on what kind of setting the sentence is describing.

A learner would usually want these dictionary entries:

• porta, portae = gate, door
• inferus, -a, -um = lower, below
• claudo, claudere, clausi, clausum = close
• sum, esse, fui = be

This is a useful habit in Latin: when you meet a word in a sentence, try to identify its full dictionary form, not just the form you see in that one sentence.