Ο ασθενής περιμένει ήρεμα τη γιατρό στο νοσοκομείο.

No. ασθενής can refer to either a male or a female patient. The article shows the gender here:

• ο ασθενής = a male patient
• η ασθενής = a female patient

So in this sentence, ο tells you the patient is masculine.

περιμένει is the 3rd person singular present of περιμένω.

With this subject, it means:

• he waits
• he is waiting

Modern Greek present tense can cover both the simple present and the progressive meaning, so Greek does not need a separate word like English is here.

Because περιμένω normally takes a direct object in Greek.

English says wait for the doctor.
Greek says, more literally, wait the doctor.

So τη γιατρό is the object of περιμένει, and that is why it appears in the accusative.

Because the doctor is feminine here.

Greek can use γιατρός for both a male and a female doctor, and the article shows the gender:

• ο γιατρός = male doctor
• η γιατρός = female doctor

Since the doctor in this sentence is feminine and also the object of the verb, you get τη γιατρό.

γιατρός is the nominative form, which is the form used for the subject.

Here, the doctor is the object of the verb, so Greek uses the accusative form:

• nominative: η γιατρός
• accusative: τη γιατρό

This pattern is common with feminine nouns of this type.

In Modern Greek, the final -ν in words like την is often dropped before certain consonants in everyday speech and writing.

So both of these may be seen:

• τη γιατρό
• την γιατρό

In this sentence, τη γιατρό is completely natural. Some speakers and writers prefer to keep την more often, especially in more formal style.

ήρεμα is an adverb meaning calmly. It tells you how the patient is waiting.

It is related to the adjective ήρεμος, ήρεμη, ήρεμο, meaning calm.

So:

• ήρεμος ασθενής = a calm patient
• περιμένει ήρεμα = waits calmly

That word order is very natural in Greek.

Greek word order is more flexible than English word order, so adverbs can move around more easily. In this sentence, περιμένει ήρεμα τη γιατρό sounds neutral and normal: verb, then adverb, then object.

Other orders are possible, but they may sound more marked or emphasize a different part of the sentence.

στο is a contraction of σε + το.

• σε = a preposition that can mean in, at, or to
• το = the for a neuter singular noun

So:

• σε το νοσοκομείο becomes στο νοσοκομείο

This contraction is standard and very common.

Because σε is a broad preposition in Greek. Its exact meaning depends on context.

It can express:

• location: in / at
• direction: to

Here the patient is already waiting there, so it expresses location: at the hospital or in the hospital, depending on the context.

In Modern Greek, the written accent shows which syllable is stressed.

For example:

• ασθενής
• περιμένει
• ήρεμα
• γιατρό
• νοσοκομείο

This is very helpful for pronunciation. Short function words like ο and στο normally do not carry a written accent.