Ważność wygasła wczoraj.

Here, ważność means validity — for example, the validity of a document, permit, contract, card, or certificate.

In other contexts, ważność can also mean importance, so the exact meaning depends on context. In this sentence, it clearly means validity.

Because ważność is a feminine singular noun, and in the past tense Polish verbs agree with the subject in gender and number.

So:

• ważność = feminine singular
• past tense of wygasnąć must match it
• therefore: wygasła

Compare:

• umowa wygasła = the contract expired
• paszport wygasł = the passport expired
• pozwolenie wygasło = the permit expired

The dictionary form is wygasnąć.

That verb means to expire, to lapse, or literally in some contexts to go out / die out.

In this sentence:

• wygasnąć = infinitive
• wygasła = past tense, feminine singular

It is perfective.

That fits well here because the sentence talks about a completed event: the validity expired yesterday.

A common imperfective partner is wygasać:

• Ważność wygasa jutro. = The validity expires tomorrow / is due to expire tomorrow.
• Ważność wygasła wczoraj. = The validity expired yesterday.

So:

• wygasać = imperfective
• wygasnąć = perfective

Because Polish does not use articles like a, an, or the.

So Ważność wygasła wczoraj can mean:

• The validity expired yesterday
• Validity expired yesterday

The exact interpretation comes from context.

Wczoraj is an adverb meaning yesterday.

It does not change its form for case, gender, or number.

It tells you when the action happened:

• wygasła = expired
• wczoraj = yesterday

No, Polish word order is fairly flexible.

This version is neutral and natural:

• Ważność wygasła wczoraj.

But you could also say:

• Wczoraj ważność wygasła.
• Ważność wczoraj wygasła.

These alternatives may sound more marked, depending on what you want to emphasize. The original sentence is probably the most straightforward and neutral.

Yes, but that is a slightly different structure.

Common alternatives include:

• Ważność wygasła wczoraj.
• Dokument stracił ważność wczoraj. = The document lost its validity yesterday.
• Ważność dokumentu wygasła wczoraj.

A very natural Polish expression is stracić ważność = to lose validity / to expire.

So Polish often expresses this idea in more than one way.

Yes, especially in administrative, legal, or bureaucratic contexts.

If the object is obvious from context, Polish can simply say:

• Ważność wygasła wczoraj.

But very often speakers would make it more explicit, for example:

• Ważność dokumentu wygasła wczoraj.
• Ważność paszportu wygasła wczoraj.
• Ważność umowy wygasła wczoraj.

So the shorter sentence is possible, but context matters.

A rough pronunciation guide is:

• Ważność ≈ VAZH-noshch
• wygasła ≈ vih-GAS-wa
• wczoraj ≈ FCHO-rai or VCHO-rai, depending on how narrowly you represent the sounds

A few useful notes:

• ż sounds like the s in measure
• cz sounds like ch in chop, but harder
• ą and ę are nasal vowels, though in real speech their pronunciation changes depending on the following sound
• Polish stress is usually on the penultimate syllable:
  • WAŻ-ność
  • wy-GAS-ła
  • WCZO-raj

Not always.

It can mean:

• validity — especially for documents, permissions, contracts, offers
• importance — in some other contexts

That is why context is important.

In official or administrative language, ważność very often means validity period or the state of being valid.

Because Polish normally uses the simple past tense here:

• wygasła

That is enough to mean expired.

Polish does not build past tenses the way English sometimes does with forms like had expired or older-style was expired. If you want had expired, Polish usually expresses that through context or with time markers rather than with a special compound tense.

So Ważność wygasła wczoraj is the normal, natural way to say it.

It is in the nominative singular, because it is the subject of the sentence.

You can tell from the structure:

• ważność = the thing that expired
• wygasła = expired

So the sentence is built like:

• subject + verb + time expression

It sounds neutral to somewhat formal, mainly because of the vocabulary.

The verb wygasnąć and the noun ważność are very common in official or administrative language. You often see them with things like:

• documents
• contracts
• memberships
• licenses
• offers

In everyday speech, people may sometimes choose simpler or more explicit wording, depending on what exactly expired.