Bolesni pacijent čeka lekara.

Because lekara is the form used for a masculine animate direct object.

• lekar = dictionary form, nominative singular
• lekara = accusative singular for an animate masculine noun

In this sentence, lekara is the object of čeka (waits for / is waiting for), so Serbian changes the noun form.

A very important pattern in Serbian is:

• masculine animate accusative = genitive form
• masculine inanimate accusative = nominative form

So:

• Vidim lekara. = I see the doctor.
• Vidim sto. = I see the table.

Here lekar is animate, so it becomes lekara.

Because the Serbian verb čekati takes a direct object, while English uses wait for.

So English says:

• The patient is waiting for the doctor.

But Serbian literally structures it more like:

• The patient waits the doctor.

That is why you get:

• čeka lekara

and not something with a separate word meaning for.

This is a very common thing to learn with Serbian verbs: you often cannot translate prepositions word-for-word from English. You need to learn which case or construction each Serbian verb requires.

pacijent is in the nominative singular. It is the subject of the sentence.

You can tell because:

• it is the one doing the action
• the verb čeka agrees with it in third person singular
• pacijent is also the basic dictionary form of the noun

So the sentence breaks down like this:

• Bolesni pacijent = the sick patient → subject
• čeka = waits / is waiting
• lekara = doctor → direct object

čeka is the 3rd person singular present tense of the verb čekati (to wait).

So:

• ja čekam = I wait / I am waiting
• ti čekaš = you wait
• on/ona/ono čeka = he/she/it waits

Since pacijent is singular, the verb is also singular: čeka.

In English, this form can often be translated either as:

• waits
• is waiting

depending on context.

It can mean either one, depending on context.

Serbian present tense often covers both:

• a general/habitual meaning: waits
• an action happening now: is waiting

So Bolesni pacijent čeka lekara. could mean:

• The sick patient waits for the doctor.
• The sick patient is waiting for the doctor.

Without more context, both are possible.

This is a very natural question, because learners often meet both forms.

Both bolestan and bolesni are related forms of the adjective sick/ill. In modern Serbian:

• bolestan is very common, especially in predicative use:
  • Pacijent je bolestan. = The patient is sick.
• bolesni is also common, especially before a noun:
  • bolesni pacijent = the sick patient

So in this sentence, bolesni pacijent is a normal phrase.

A useful beginner shortcut is:

• after je (is), you will often see bolestan
• before a noun, bolesni is very common

Also, bolesni agrees with pacijent in:

• gender: masculine
• number: singular
• case: nominative

In Serbian, adjectives must agree with the noun they describe.

Here, pacijent is:

• masculine
• singular
• nominative

So the adjective also appears in a matching form:

• bolesni pacijent

If the noun changed, the adjective would change too. For example:

• bolesna žena = sick woman
• bolesno dete = sick child
• bolesni pacijenti = sick patients

Agreement is one of the most important features of Serbian grammar.

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

So:

• pacijent can mean a patient or the patient
• lekara can mean a doctor or the doctor

Which meaning is intended depends on context.

That means Bolesni pacijent čeka lekara. could be understood as:

• A sick patient is waiting for a doctor.
• The sick patient is waiting for the doctor.

In real use, the surrounding situation usually makes it clear.

Yes. Serbian word order is more flexible than English word order because case endings show who is doing what.

The neutral, most straightforward order here is:

• Bolesni pacijent čeka lekara.

But other orders are possible, for example:

• Lekara čeka bolesni pacijent.
• Bolesni pacijent lekara čeka.

These alternatives usually change the focus or emphasis, not the basic meaning.

For a learner, the best default is to use the neutral order:

subject + verb + object

A simple approximation is:

• čeka ≈ CHEH-kah
• lekara ≈ LEH-kah-rah

A few pronunciation notes:

• č sounds like ch in chocolate, but a bit firmer
• Serbian stress is not marked in normal spelling, so beginners usually learn it by listening
• Each written vowel is pronounced clearly:
  • e = eh
  • a = ah

Also, Serbian spelling is very phonetic, so once you know the sound of each letter, pronunciation becomes much easier than in English.

Yes, very often you can.

Both words can mean doctor, but there is a slight difference in feel:

• lekar = physician, doctor; often a bit more formal or standard
• doktor = doctor; very common in everyday speech

So these are both natural:

• Bolesni pacijent čeka lekara.
• Bolesni pacijent čeka doktora.

The grammar is the same in both cases:

• lekar → lekara
• doktor → doktora

because both are masculine animate nouns in the accusative singular.