Ne mogu odrediti je li ova riječ imenica ili glagol.

Literally, it means I cannot determine or I’m not able to determine.

• ne = not
• mogu = I can / I am able
• odrediti = to determine

So the first part is a very common Croatian structure:

• mogu + infinitive = can + verb
• ne mogu + infinitive = cannot + verb

In Croatian, mogu is indeed the correct 1st person singular form of moći (to be able, can).

Present tense of moći:

• ja mogu = I can
• ti možeš = you can
• on/ona/ono može = he/she/it can
• mi možemo = we can
• vi možete = you (plural/formal) can
• oni/one/ona mogu = they can

So mogu can mean either I can or they can, depending on context. Here, with no subject stated, it means I can, because Croatian often omits subject pronouns when the meaning is clear.

Because after the modal verb moći (can / be able to), Croatian normally uses the infinitive.

So:

• mogu odrediti = I can determine
• ne mogu odrediti = I can’t determine

This is similar to English can determine.

Here je li introduces an indirect yes/no question, so it means whether.

So:

• je li ova riječ imenica ili glagol = whether this word is a noun or a verb

You can think of je li as a structure connected to is it / whether.

In direct questions:

• Je li ovo imenica? = Is this a noun?

In indirect questions:

• Ne znam je li ovo imenica. = I don’t know whether this is a noun.

In standard Croatian, it should be written as two words: je li.

• je li = correct standard spelling
• jeli = very common in informal writing, but not standard in careful written Croatian

So in a sentence like this, je li is the correct form.

Yes, many speakers say da li, especially in everyday speech:

• Ne mogu odrediti da li je ova riječ imenica ili glagol.

But in standard Croatian, especially in more careful or formal usage, je li is often preferred.

Also notice that with da li, you usually include je separately:

• da li je ova riječ...

With je li, the je is already part of the expression:

• je li ova riječ...

Because ova is the feminine singular form of this, and riječ (word) is a feminine noun.

Agreement:

• ovaj = masculine singular
• ova = feminine singular
• ovo = neuter singular

Since riječ is feminine:

• ova riječ = this word

You usually learn a noun’s gender as part of its vocabulary entry, but there are also clues.

Riječ is feminine, and its adjective/demonstrative agrees with it:

• ova riječ

That agreement tells you the noun is feminine.

Be careful: Croatian noun gender is grammatical, not based on meaning. A word does not need to refer to a female person in order to be feminine.

Here riječ is in the nominative singular, because it is the subject of the clause:

• je li ova riječ imenica ili glagol
• literally: whether this word is a noun or a verb

So ova riječ is the thing being identified.

You would see other forms in other contexts, for example:

• bez riječi = without words
• o riječi = about the word
• te riječi = those words or of that word, depending on context

But in this sentence, nominative singular is the normal form.

Because after to be in this kind of sentence, Croatian usually uses the nominative for predicate nouns.

So:

• ova riječ je imenica = this word is a noun
• ova riječ je glagol = this word is a verb

That is why the alternatives are:

• imenica ili glagol

Both are in their dictionary/basic form.

Because Croatian does not need to repeat it here.

• je li ova riječ imenica ili glagol
  means
• whether this word is a noun or a verb

The verb je is understood with both options. This is completely natural and normal.

English does the same:

• whether this word is a noun or a verb not
• whether this word is a noun or is a verb
  although the repeated is is also possible for emphasis.

Yes, Croatian word order is more flexible than English, but this sentence is very natural and neutral.

Standard order:

• Ne mogu odrediti je li ova riječ imenica ili glagol.

Croatian often puts clitics like je in certain positions, so not every rearrangement sounds equally natural. This sentence already has a very standard structure:

1. main clause: Ne mogu odrediti
2. subordinate clause: je li ova riječ imenica ili glagol

So while Croatian does allow some flexibility, this version is a good one to learn.

Odrediti is perfective.

That means it refers to determining something as a completed result: reaching a conclusion.

Here that fits well:

• Ne mogu odrediti... = I can’t determine... / I can’t figure out...

An imperfective counterpart would be something like određivati, but that would not sound as natural here.

So yes, aspect matters, and odrediti is the normal choice in this sentence.

It is literally I can’t determine, but in natural English it can often be translated as:

• I can’t tell whether this word is a noun or a verb.
• I can’t determine whether this word is a noun or a verb.

So can’t tell is often the most natural everyday translation, while can’t determine is a bit more formal or analytical.

A rough pronunciation guide:

• Ne ≈ neh
• mogu ≈ MOH-goo
• odrediti ≈ od-REH-dee-tee
• je li ≈ yeh lee
• ova ≈ OH-vah
• riječ ≈ ree-etch (the final sound is like a softer ch, but not exactly English ch)
• imenica ≈ ee-meh-NEE-tsah
• ili ≈ EE-lee
• glagol ≈ GLAH-gol

Stress in Croatian is not always easy for beginners, but this approximation is enough to help you get started.

Yes, and that is exactly what the sentence does.

Croatian usually omits subject pronouns when the verb form already makes the subject clear.

So:

• (Ja) ne mogu odrediti...

Both are possible, but the version without ja is more natural unless you want emphasis:

• Ja ne mogu odrediti... = I can’t determine...
  with extra emphasis on I

Usually yes, riječ means word, but it can also mean speech, remark, or promise depending on context, just like English word can have extended meanings.

In this sentence, though, it very clearly means a vocabulary item or lexical word:

• ova riječ = this word

So here there is no ambiguity.

The part je li ova riječ imenica ili glagol is a subordinate clause, more specifically an indirect question.

Whole sentence structure:

• main clause: Ne mogu odrediti
• indirect question: je li ova riječ imenica ili glagol

This is very common in Croatian:

• Ne znam je li... = I don’t know whether...
• Pitam se je li... = I wonder whether...
• Ne mogu odrediti je li... = I can’t determine whether...