Drugi autobus kasni.

In this sentence, drugi most naturally means the second:

• Drugi autobus kasni. = The second bus is late.

However, drugi can also mean another / the other in some contexts. Serbian often relies on context to make the exact meaning clear.

For example:

• Čekam drugi autobus. can mean I’m waiting for another bus or the second bus, depending on the situation.

So the word itself can have more than one translation, but in a simple sentence like this, learners are often first taught second.

Because drugi is an adjective, and it must agree with autobus in:

• gender
• number
• case

Here:

• autobus is masculine
• singular
• nominative case (the subject of the sentence)

So the adjective also takes the masculine singular nominative form:

• drugi autobus

Compare:

• drugi autobus = masculine singular
• druga knjiga = feminine singular
• drugo pitanje = neuter singular
• drugi autobusi = masculine plural

It is in the nominative case.

That’s because autobus is the subject of the sentence — it is the thing doing the action/state:

• Drugi autobus kasni.
• The second bus is late.

A good clue is that both words are in their dictionary/basic form here:

• drugi
• autobus

If you changed the sentence so autobus was an object, the case would probably change. For example:

• Čekam drugi autobus. = I’m waiting for the second/another bus.

There, autobus is in the accusative, though for many masculine inanimate nouns the accusative looks the same as the nominative.

Serbian does not have articles like English a/an and the.

So:

• autobus can mean a bus or the bus
• drugi autobus can mean a second bus, the second bus, or sometimes another bus, depending on context

Serbian speakers understand definiteness from:

• context
• word order
• stress/emphasis
• surrounding information

That is very normal in Serbian. You do not need to add a separate word for the.

Kasni comes from the verb kasniti, which means:

• to be late
• to run late
• sometimes to delay / lag behind, depending on context

In this sentence:

• Drugi autobus kasni. = The second bus is late / The second bus is running late

So kasni is the 3rd person singular present tense form, used with autobus:

• ja kasnim = I am late
• ti kasniš = you are late
• on/ona/ono kasni = he/she/it is late

Since autobus is singular, you use kasni.

Because Serbian uses a simple present tense form where English often uses to be + adjective.

English:

• The bus is late.

Serbian:

• Autobus kasni.

So instead of using a separate verb to be plus an adjective, Serbian often uses the verb kasniti directly.

This is very common and natural. You should learn kasniti as a full verb meaning to be late.

Yes. Serbian word order is more flexible than English because case endings help show grammatical roles.

The neutral, most straightforward order is:

• Drugi autobus kasni.

But you may also hear:

• Kasni drugi autobus.

This version can sound more like:

• It’s the second bus that’s late
• or it puts a bit more focus on the fact of being late

So both are possible, but Drugi autobus kasni is the best basic order for learners to remember first.

You usually learn the noun’s gender as part of the word.

Here, autobus is masculine. Many masculine Serbian nouns end in a consonant, and autobus does:

• autobus

That pattern often suggests masculine gender, though it’s still best to learn gender with each noun.

Because it is masculine, the adjective must match:

• drugi autobus

If the noun were feminine, you would need a different adjective form:

• druga stanica = the second stop

It is an international loanword, and it looks very similar to English bus / autobus and many European equivalents.

In Serbian, autobus is a normal everyday word meaning bus.

You may also hear related forms such as:

• autobusi = buses
• autobusa = of the bus / buses, depending on context
• autobusom = by bus / with the bus

So even though the word may look familiar to an English speaker, it still behaves like a regular Serbian noun.

You can say:

• Drugi autobus ne kasni.

Serbian usually makes negation by putting ne before the verb:

• kasni = is late
• ne kasni = is not late

So:

• Drugi autobus kasni. = The second bus is late.
• Drugi autobus ne kasni. = The second bus is not late.

A simple way is:

• Da li drugi autobus kasni?

This is a very common yes/no question pattern in Serbian:

• Da li + sentence

You may also hear:

• Kasni li drugi autobus?

That is also correct, but Da li drugi autobus kasni? is often easier for learners to use at first.