Дверной проём уже измерили.

Not quite.

• дверь = door
• дверной проём = doorway, door opening, or the opening in the wall for a door

So this sentence is about measuring the opening, not the physical door itself.

Дверной is an adjective meaning door- or related to a door.

So:

• дверь = door
• дверной проём = door opening / doorway

Russian often uses an adjective where English might use a noun as a modifier. Compare:

• дверная ручка = door handle
• дверной замок = door lock
• дверной проём = doorway / door opening

So дверной is the normal adjective form here.

It is in the accusative case, because it is the direct object of измерили (measured).

However, for a masculine inanimate singular noun, the accusative looks exactly like the nominative:

• nominative: дверной проём
• accusative: дверной проём

So the form does not change, even though the function does.

The adjective дверной also matches the noun, and here its accusative form is the same as its nominative form.

Because измерили does not agree with дверной проём here.

The noun дверной проём is the object, not the subject.

The verb is in past plural, and Russian often uses this kind of plural verb with no stated subject to mean something like:

• they measured it
• someone measured it
• it has been measured

This is a very common Russian way to express an action when the doer is unknown, unimportant, or obvious from context.

So the sentence literally looks like:

• The doorway already measured-they

but naturally means:

• The doorway has already been measured
• They already measured the doorway

Because Russian often leaves the doer unspecified in this kind of sentence.

Измерили in the plural can work like an indefinite-personal construction: the action happened, but the speaker does not name who did it.

This is common in everyday Russian. Similar examples:

• Мне звонили. = Someone called me.
• Документы уже отправили. = The documents have already been sent / Someone already sent the documents.
• Дверной проём уже измерили. = The doorway has already been measured.

So this structure is normal and natural.

This is about aspect.

• измерить / измерили = perfective
  Focuses on the action as completed
• мерить / мерили = imperfective
  Focuses more on the process, repetition, or ongoing action

Here, the idea is that the measuring is already done, so измерили is the natural choice.

Compare:

• Дверной проём уже измерили. = The doorway has already been measured.
• Дверной проём мерили. = They were measuring / measured the doorway
  This sounds more process-oriented or less clearly completed.

Because of уже (already), the perfective verb fits especially well.

Уже means already.

It tells you that the action was completed before now, often earlier than expected or relevant to the current situation.

So:

• Дверной проём измерили. = They measured the doorway.
• Дверной проём уже измерили. = They already measured the doorway.

In English, already often helps create the same feeling.

Yes. Russian word order is flexible, though different orders can change the emphasis.

The neutral order here is:

• Дверной проём уже измерили.

Other possible orders:

• Уже измерили дверной проём.
• Дверной проём измерили уже.

These are all possible, but the emphasis shifts a bit.

For example:

• Уже измерили дверной проём can sound like the speaker is emphasizing that the measuring is already done.
• Дверной проём уже измерили is a very natural, neutral statement.

So yes, the order can move, but the original sentence is perfectly standard.

Yes, very naturally.

Even though Russian uses an active plural verb, English will often prefer a passive translation:

• The doorway has already been measured.

A more literal translation is:

• They already measured the doorway.

Both are valid, but the passive often sounds more natural in English when the doer is unspecified.

Проём is pronounced roughly like pra-YOM.

Important points:

• the stress is on ём
• ё is pronounced like yo
• ё always indicates stress when it is written

So:

• проём = pra-YOM

In many Russian texts, ё is often written as е, so you may also see проем, but проём is the more precise spelling.

Yes. For example:

• Дверной проём уже измерен.

This means The doorway has already been measured too.

The difference is style and structure:

• Дверной проём уже измерили.
  literally They already measured the doorway; very common, conversational, natural
• Дверной проём уже измерен.
  more explicitly passive; can sound a bit more formal or result-focused

In everyday speech, the original sentence with измерили is extremely normal.

Russian has no articles like a or the.

So дверной проём can mean:

• a doorway
• the doorway

Context tells you which one is meant. In this sentence, English will usually use the:

• The doorway has already been measured.

That definiteness is understood from the situation, not from a separate word.