Он потерял сознание.

• Он = he
• потерял = lost
• сознание = consciousness

So the whole sentence literally means He lost consciousness.

Потерял is the perfective past form of потерять, which means to lose in the sense of a completed result.

That fits this sentence because the focus is on the event happening: he lost consciousness.

Compare:

• Он потерял сознание = He lost consciousness / He passed out
• Он терял сознание = He was losing consciousness / He kept losing consciousness

So потерял describes a completed event, while терял would describe a process or repeated situation.

In Russian, the past tense is usually formed with -л.

Here:

• infinitive: потерять = to lose
• past masculine singular: потерял = lost (he lost)

The ending changes for gender and number:

• он потерял = he lost
• она потеряла = she lost
• оно потеряло = it lost
• они потеряли = they lost

So потерял tells you the subject is masculine singular.

Because сознание is the direct object of потерял.

The verb потерять takes an object in the accusative case.
Here, сознание is a neuter noun, and in the singular its nominative and accusative forms are the same:

• nominative: сознание
• accusative: сознание

So the case is accusative, even though the form looks unchanged.

Сознание means consciousness, awareness, or conscious state, depending on context.

In this sentence, it means physical consciousness: being awake and aware, not unconscious.

So потерять сознание is the normal expression for to lose consciousness.

Yes, very much so.

It is a standard, natural Russian expression meaning:

• to lose consciousness
• to faint
• to pass out

It is not a weird literal phrase that Russians avoid. It is exactly the kind of phrase you would expect to hear in everyday speech, news, or medical contexts.

It sounds mostly neutral.

Он потерял сознание works in:

• everyday conversation
• written narratives
• news reports
• medical contexts

A more conversational English equivalent might be He passed out, but the Russian sentence itself is not especially slangy.

Yes, often it can be omitted if the subject is already clear from context.

For example:

• Потерял сознание прямо на улице. = He lost consciousness right in the street.

Russian often drops subject pronouns when the context makes them obvious.

But if you want to state the subject clearly or contrast it with someone else, он is perfectly normal.

Yes. Russian word order is flexible.

The most neutral order here is:

• Он потерял сознание.

But you may also see:

• Сознание он потерял.
• Потерял он сознание.

These alternatives change the emphasis, not the basic meaning.

For a learner, Он потерял сознание is the best default order to use.

Russian has no articles like a or the.

So сознание can correspond to:

• consciousness
• the consciousness
• sometimes an understood definite idea from context

In this expression, English naturally says lost consciousness without an article too, so the translation matches nicely.

You usually should not say that.

Russian normally says simply:

• Он потерял сознание

Adding своё sounds unnecessary and unnatural in most contexts, because it is already obvious whose consciousness is being discussed.

Russian often avoids possessives where English learners might be tempted to add them.

Often yes, in practical meaning.

But there is a slight difference:

• Он потерял сознание = He lost consciousness
• Он упал в обморок = He fainted / He fell into a faint

In many real situations they overlap, but потерял сознание focuses on the state of becoming unconscious, while упал в обморок is a very common way to say someone fainted.

Yes. Some common alternatives are:

• Он упал в обморок. = He fainted.
• Он лишился сознания. = He lost consciousness.
  This is a bit more formal or literary.
• Он отключился. = He blacked out / passed out.
  More colloquial, depending on context.

But Он потерял сознание is one of the most standard and widely useful versions.

A rough stress guide:

• он
• потеря́л
• созна́ние

The main stress falls on:

• -я́л in потерял
• -на́- in сознание

A rough English-style approximation might be:

• on pa-tyir-YAL saz-NA-ni-ye

But it is much better to learn the stress than rely too much on English approximation.

The infinitive is потерять = to lose.

So:

• потерять = infinitive
• потерял = past masculine singular

This is useful because you can then build other forms:

• я потерял = I lost
• ты потерял = you lost
• он потерял = he lost
• она потеряла = she lost

Usually, in this exact phrase, people understand it literally as becoming unconscious.

The noun сознание can have broader meanings like consciousness or awareness, but потерять сознание is a very established expression for physically losing consciousness.

So unless the context is very unusual, listeners will take it literally.

In this expression, no. It functions like an abstract noun, similar to English consciousness.

You do not normally think of it as a consciousness here. It is just the state of being conscious.

That is why потерять сознание works as a fixed abstract phrase.

Yes. It is completely appropriate.

For example:

• Он потерял сознание! = He lost consciousness!
• Она потеряла сознание и не дышит. = She lost consciousness and isn’t breathing.

So this is a very useful sentence in practical Russian.