No, nevím.

Not exactly. In No, nevím., No is usually a conversational particle, not a straight translation of English no.

Here it often means something like:

• well
• so
• you know
• a hesitation before answering

So No, nevím. is often closer to Well, I don't know. than to a firm No, I don't know.

Czech no can have different tones depending on context, so it is a very common little word with several uses.

A simple pronunciation guide is:

• No ≈ no in English, but with a clear short o
• nevím ≈ NEH-veem

More precisely:

• ne sounds like neh
• vím has a long í, so it sounds like veem

Stress in Czech normally falls on the first syllable of the word:

• NE-vím

So the whole sentence is roughly:

NO, NEH-veem.

Nevím is the 1st person singular present tense form of the verb vědět, meaning to know.

So:

• vím = I know
• nevím = I do not know / I don't know

It is one complete verb form, so the subject I is already built in. Czech usually does not need a separate subject pronoun here.

In Czech, verb negation is usually formed by adding ne- directly to the verb.

So:

• vím = I know
• nevím = I don't know

This is normal Czech grammar. Unlike English, which uses a separate word (do not know), Czech often makes the negative part of the verb itself.

The infinitive is vědět, which means to know.

A few useful forms are:

• vědět = to know
• vím = I know
• víš = you know
• ví = he/she/it knows
• nevím = I don't know

This verb is somewhat irregular, so learners usually memorize its common forms rather than trying to build all of them mechanically at first.

Because Czech verb endings usually show the subject clearly.

In nevím, the ending already tells you it means I don't know. So já is unnecessary unless you want emphasis.

Compare:

• Nevím. = I don't know.
• Já nevím. = I don't know / Me, I don't know (more emphasis)

Czech often leaves out subject pronouns when they are obvious from the verb.

Yes. Both are correct.

• Nevím. = neutral, normal
• Já nevím. = more emphatic, contrasting, or emotionally marked
• No, já nevím. = Well, I don't know with extra emphasis

So if you just want the basic statement, Nevím is usually enough.

The comma separates the discourse particle No from the main clause.

So in:

No, nevím.

the No functions like an introductory word such as Well, in English. Czech writing often marks that with a comma.

It is neutral and very common in everyday speech.

• Nevím. is completely standard.
• Adding No makes it sound more conversational and natural in spoken Czech.

It is not rude by itself, but tone matters. Depending on how you say it, it can sound:

• thoughtful
• hesitant
• dismissive
• casual

So the words are simple and normal, but intonation carries a lot of meaning.

Yes, and this confuses many learners.

Czech no can sometimes be a particle meaning something like:

• well
• of course
• right
• come on

So in other contexts, No! can sound more like Well, yes! or Sure!

But in No, nevím., it is best understood as a discourse filler like Well, ...

This is one reason learners should not always translate Czech no directly as English no.

Only nevím is standard spelling.

• nevím = correct
• nevim = nonstandard, informal texting-style spelling

The long í matters in proper Czech writing, so you should write nevím.

Yes. It is a complete and natural sentence.

• nevím is a full finite verb form meaning I don't know
• No is an optional conversational addition

So both of these are complete:

• Nevím.
• No, nevím.

The second one just sounds a little more like spoken interaction.