Nie chcę stracić dokumentu.

Chcę means I want.

It is the 1st person singular present form of the verb chcieć (to want). The ending -ę tells you the subject is I, so Polish does not need a separate ja here.

Because Polish often drops subject pronouns when they are clear from the verb ending.

So:

• chcę = I want
• nie chcę = I do not want / I don't want

You can add ja for emphasis or contrast:

• Ja nie chcę stracić dokumentu = I don't want to lose the document

That sounds more emphatic than the neutral version.

Stracić is the infinitive, so it means to lose.

After chcieć (to want), Polish normally uses an infinitive:

• chcę stracić = I want to lose
• chcę kupić = I want to buy
• chcę iść = I want to go

So the structure is very similar to English: want + to + verb.

This is about aspect, which is very important in Polish.

• stracić = perfective
• tracić = imperfective

Here, stracić is used because it refers to one complete loss: the document ends up lost.

Very roughly:

• stracić dokument = to lose the document as a completed event
• tracić dokument = to be losing the document, to lose documents repeatedly, or something more ongoing/general

In this sentence, the speaker means a single result they want to avoid, so stracić is the natural choice.

Because Polish often uses the genitive after negation.

Without negation, the direct object of stracić would normally be dokument.

But in:

• Nie chcę stracić dokumentu

the negation nie makes dokument change to the genitive singular form dokumentu.

So:

• dokument = basic form
• dokumentu = genitive singular

This is a very common Polish pattern and often surprises English speakers.

It is genitive singular.

The noun dokument is a masculine inanimate noun, and in the genitive singular it becomes dokumentu.

So the sentence contains:

• Nie chcę = I don't want
• stracić = to lose
• dokumentu = of the document / the document in genitive after negation

Even if English does not show this kind of case change, Polish does.

Polish has no articles, so the sentence itself does not directly tell you the or a.

So Nie chcę stracić dokumentu could mean:

• I don't want to lose the document
• I don't want to lose a document

Context decides.

If you want to be more specific, Polish can add words like:

• tego dokumentu = this / that document
• mojego dokumentu = my document

A rough English-friendly approximation is:

Nyeh h-tseh STRA-chich doku-MEN-too

A few helpful points:

• nie sounds roughly like nyeh
• ch is like the sound in Scottish loch or German Bach
• c sounds like ts
• ć is a soft sound, a bit like a very soft ch
• ę is a nasal vowel, though in everyday speech it is often less strongly nasal than textbooks suggest

Stress:

• STRAcić
• dokuMENtu

Polish stress is usually on the second-to-last syllable.

Yes. Polish word order is more flexible than English word order.

The version you have:

• Nie chcę stracić dokumentu

is the most neutral and natural order.

You can move things for emphasis, for example:

• Dokumentu nie chcę stracić

This puts more focus on the document.

So the meaning stays basically the same, but the emphasis changes.

Yes, and in many situations that would sound very natural.

There is a slight difference:

• stracić = to lose in a broad sense
• zgubić = to lose / misplace something physical

So if you mean that you might accidentally misplace a passport, ID card, or paper, zgubić dokument is very common.

• Nie chcę zgubić dokumentu = I don't want to lose/misplace the document

Meanwhile, stracić dokumentu is a bit broader and can sound more general.