Por poco el heredero perdió la copia autorizada.

Por poco means almost, nearly, or just barely.

So Por poco el heredero perdió la copia autorizada means that the heir came very close to losing the certified copy, but in the end did not lose it.

A very natural English gloss is:

• The heir almost lost the certified copy.
• The heir nearly lost the certified copy.

In Spanish, por poco often introduces a situation that was very close to happening but did not happen.

Examples:

• Por poco me caigo. = I almost fell.
• Por poco llegamos tarde. = We almost arrived late.

Putting por poco at the beginning is very common because it sets up the main idea straight away: something almost happened.

Spanish often places expressions like this before the subject and verb:

• Por poco el heredero perdió la copia autorizada.
• El heredero por poco perdió la copia autorizada.

Both are possible. The first version sounds slightly more natural if the speaker wants to emphasize the near miss.

So the word order is flexible, but sentence-initial por poco is very normal.

Perdió is the preterite of perder (to lose). The preterite is used because the sentence refers to a specific past event:

• perdió = he/she lost
• here, with por poco, it means he/she almost lost

The preterite fits because this was a single, completed situation in the past.

Compare:

• Por poco perdió la copia. = He almost lost the copy.
  A specific event.
• Por poco perdía la copia cada día. = He was on the verge of losing the copy every day.
  This would suggest repeated or background past situations, which is not the idea here.

Yes. Casi perdió la copia autorizada is also correct and very common.

Both casi and por poco can mean almost here, but there is often a small nuance:

• casi is the most neutral and common way to say almost
• por poco often feels a bit more dramatic, like it was a close call

So:

• Casi perdió la copia autorizada.
• Por poco perdió la copia autorizada.

Both are natural, but por poco can sound slightly more vivid.

Heredero means heir.

It comes from heredar (to inherit). In legal or family contexts, a heredero is the person who inherits property, rights, or obligations.

Forms:

• el heredero = the male heir
• la heredera = the female heir

A useful detail: the h is silent, so heredero is pronounced as if it began with a vowel sound.

Literally, yes: authorised copy. But in Spain, copia autorizada is often a legal/notarial term.

In many legal contexts, especially with notaries, a copia autorizada is an official certified copy of a document, issued with legal validity. It is not just any ordinary copy.

This is why a more natural English translation in context might be:

• certified copy
• official certified copy
• sometimes authorised copy, if the legal context is clear

In Spain, this often contrasts with copia simple, which is a simpler, non-official copy.

Because copia is a feminine noun in Spanish:

• la copia
• una copia

Any adjective describing it must agree in gender and number:

• la copia autorizada
  feminine singular noun + feminine singular adjective

So autorizada changes to match copia.

Compare:

• el documento autorizado = the authorised document
• la copia autorizada = the authorised copy

Because la copia autorizada is a direct object, but it is a thing, not a person.

Spanish uses the personal a mainly before specific people (and sometimes personified animals).

Examples:

• Vi al heredero. = I saw the heir.
  Here a appears because heredero is a person.
• Perdió la copia autorizada. = He lost the certified copy.
  No a, because copia is a thing.

So in your sentence:

• el heredero = subject
• perdió = verb
• la copia autorizada = direct object

Normally, no.

The standard sentence is:

• Por poco el heredero perdió la copia autorizada.

A comma is usually unnecessary because por poco is tightly connected to the clause that follows.

You might occasionally see a comma in writing for emphasis or rhythm, but in ordinary neutral writing, no comma is the usual choice.

Yes. Spanish often omits subject pronouns and even noun subjects when the context is clear.

So if we already know who we are talking about, you could simply say:

• Por poco perdió la copia autorizada.

That means:

• He/She almost lost the certified copy.

In your full sentence, el heredero is included because the speaker wants to identify exactly who almost lost it.

Yes. By itself, perdió can mean:

• he lost
• she lost
• it lost
• sometimes you (formal) lost

Spanish verbs do not always show the subject’s gender. In your sentence, we know it is he because the subject is explicitly stated:

• el heredero = the male heir

If it were feminine, it would be:

• Por poco la heredera perdió la copia autorizada.

Yes, several versions are possible, depending on style and emphasis:

• El heredero por poco perdió la copia autorizada.
• Casi perdió la copia autorizada el heredero.
• El heredero casi pierde la copia autorizada.
  This last one would be present tense in form, so it would need a context where that tense makes sense.

The original sentence is perfectly natural, especially if the speaker wants to emphasize that it was a near disaster:

• Por poco el heredero perdió la copia autorizada.

In sentences like this, yes: it normally means the event almost happened but did not.

So:

• Por poco el heredero perdió la copia autorizada.

implies:

• He did not lose it.
• But he came very close to losing it.

That is one of the most important things to understand about por poco in this structure.