Pojistník není pojištěný.

This is one of the most important things to notice in the sentence.

• pojistník = the policyholder, the person who takes out the insurance contract
• pojištěný = the insured person, the person who is covered by the insurance

These are often not the same person. For example:

• A parent may be the pojistník
• The child may be the pojištěný

So Czech makes a clear distinction between the person who holds the policy and the person who is insured under it.

Není is the 3rd person singular present tense of nebýt / být in the negative:

• je = is
• není = is not

So:

• Pojistník je pojištěný. = The policyholder is insured.
• Pojistník není pojištěný. = The policyholder is not insured / is not the insured person.

Because the subject pojistník is singular, Czech uses není.

It is originally an adjective meaning insured, but in sentences like this it can behave almost like a noun in English translation.

Here it is a predicate adjective after není:

• pojištěný = insured

But depending on context, English may translate it as:

• not insured
• not the insured person

So grammatically in Czech it is adjective-based, but in meaning it can point to a role or category of person.

The ending -ý shows the masculine singular form of the adjective.

It matches pojistník, which is a masculine singular noun.

So the agreement is:

• pojistník → masculine singular
• pojištěný → masculine singular form

If the subject changed, the adjective would also change:

• Pojistnice není pojištěná. = The female policyholder is not insured.
• Pojistníci nejsou pojištění. = The policyholders are not insured.

This is normal Czech adjective agreement.

Czech does not use articles like English a / an / the.

So:

• Pojistník can mean a policyholder or the policyholder
• pojištěný can mean insured or the insured person

You understand which one is meant from the context.

This is very common for English speakers to notice, because English requires articles much more often than Czech does.

Yes, it can feel a bit ambiguous when translated into English.

In Czech, pojištěný can mean:

• insured as an adjective
• the insured person in insurance terminology

So in the right context, Pojistník není pojištěný can mean either:

• the policyholder does not have insurance coverage
• the policyholder is not the person who is insured under the policy

In insurance/legal language, the second reading is often very natural.

Because with být (to be), Czech normally uses the nominative for predicate nouns and adjectives in ordinary modern usage.

So:

• Pojistník is nominative
• pojištěný is also nominative

This is similar to saying:

• On je učitel. = He is a teacher.
• On je nemocný. = He is ill.

After není, the same pattern remains:

• On není učitel.
• On není nemocný.

So pojištěný stays in the nominative form.

Yes. Czech word order is more flexible than English, though the neutral order here is very natural:

• Pojistník není pojištěný.

Other versions are possible for emphasis, for example:

• Pojištěný není pojistník.
• Pojistník pojištěný není.

These do not necessarily change the basic meaning, but they change the focus or emphasis.

For a learner, the original order is the safest and most neutral one.

A rough pronunciation guide:

• pojistník ≈ poh-yist-neek

A bit more carefully:

• po like po in pole, but shorter
• jis sounds roughly like yis
• tník has a long í, so the last syllable is stressed by length, not by English-style stress rules

The important thing is that í is a long vowel.

A rough guide:

• pojištěný ≈ poh-yish-tyeh-nee

Some details:

• š = sh
• ť is a soft t sound
• ě after ť helps create that soft sound
• ý is a long vowel, pronounced like a long ee

So the word may feel difficult at first because of ště, but that cluster is very common in Czech.

The grammar is completely normal Czech, but the vocabulary is somewhat formal and insurance-related.

In everyday conversation, people might not often say pojistník, unless they are talking specifically about contracts, policies, or legal/administrative matters.

So this sentence sounds natural, but in a specialized context such as:

• insurance documents
• contract explanations
• customer service
• legal language

It comes from the verb pojistit = to insure.

Related forms:

• pojistit = to insure
• pojištění = insurance / insuring / insured state, depending on context
• pojištěný = insured

So pojištěný is basically a form meaning insured or having been insured.

This is useful because many Czech words in this area are built from the same root pojist- / pojišť-.

You would change both the subject and the predicate part:

• Pojistníci nejsou pojištění.

That means:

• The policyholders are not insured or
• The policyholders are not the insured persons

Changes to notice:

• pojistník → pojistníci
• není → nejsou
• pojištěný → pojištění

This is a good example of how Czech changes several words at once to match number.