Nemam čime otvoriti konzervu.

Čime means with what or by means of what.

In this sentence, Nemam čime otvoriti konzervu, it gives the idea of:

• I don’t have anything to open the can with
• literally, something like I don’t have with what to open the can

Grammatically, čime is the instrumental form of što / šta used in this kind of construction.

Because Croatian often uses the instrumental case by itself to express the tool or means used to do something.

So:

• čime already includes the idea of with what
• Croatian does not need a separate preposition here

That is why čime otvoriti naturally means to open with what.

You may also hear s čim in everyday speech, but čime is the cleaner and more standard form in a sentence like this.

This is a very common pattern in Croatian:

• imam / nemam + čime / gdje / kome / kada + infinitive

So:

• nemam čime otvoriti = I have nothing to open it with
• imam gdje sjesti = I have somewhere to sit
• nemam kome pisati = I have nobody to write to

In this pattern, Croatian normally uses čime, not ničim.

Ničim can appear in other kinds of sentences, for example:

• Ne mogu to otvoriti ničim = I can’t open it with anything

So both words exist, but they are used in different structures.

Because after this kind of expression, Croatian commonly uses an infinitive.

The pattern is:

• nemam čime + infinitive
• imam što + infinitive
• nemam gdje + infinitive

So otvoriti stays in the infinitive because it means to open.

The whole structure means something like:

• I don’t have anything with which to open the can

Because otvoriti is perfective, and here Croatian is thinking about one completed result: getting the can open.

• otvoriti = to open as a completed action
• otvarati = to be opening / to open repeatedly / to open in general

In this situation, the speaker means one specific act of opening one can, so otvoriti is the natural choice.

Because konzervu is the accusative singular form, and it is the direct object of otvoriti.

The base form is:

• konzerva = can / tin

But after otvoriti you need the object form:

• otvoriti konzervu = to open a/the can

So:

• nominative: konzerva
• accusative: konzervu

Because Croatian usually leaves out subject pronouns when the verb ending already shows who the subject is.

• nemam already means I do not have

So ja is unnecessary unless you want emphasis or contrast.

For example:

• Ja nemam čime otvoriti konzervu, ali on ima.
• I don’t have anything to open the can with, but he does.

Without emphasis, just Nemam... is the normal way to say it.

Croatian has no articles.

So konzervu can mean:

• a can
• the can

The exact meaning depends on context.

English forces you to choose between a and the, but Croatian usually does not mark that explicitly.

Yes.

• imam = I have
• nemam = I do not have

In Croatian, the negative is normally formed with ne-, which joins directly to the verb in forms like this:

• imam → nemam
• mogu → ne mogu
  
  • this one is written separately

So nemam is the standard negative form, not ne imam.

Yes, but it means something slightly different.

• Nemam čime otvoriti konzervu = I don’t have anything to open the can with
• Ne mogu otvoriti konzervu = I can’t open the can

The second sentence is broader. Maybe you are too weak, maybe the can is stuck, maybe you lack a tool. The first sentence specifically points to the lack of a means or instrument.

Yes. Croatian word order is fairly flexible, and moving words changes the emphasis more than the basic meaning.

The sentence as given:

• Nemam čime otvoriti konzervu.

is natural and neutral.

You could also say:

• Konzervu nemam čime otvoriti.

This puts more emphasis on the can.

So the original order is a good default, but other orders are possible depending on what the speaker wants to highlight.