Learn Hardcore German: Meine Schwester arbeitet ehrenamtlich im Krankenhaus. - My sister works as a volunteer in the hospital.

In German, the possessive word (mein, dein, sein, etc.) changes its ending to agree with the gender, number, and case of the noun it belongs to.

Schwester is feminine: die Schwester.
In this sentence, Schwester is the subject, so it is in the nominative case.
The nominative feminine form of mein is meine.

So you get:

mein Bruder (my brother – masculine, nominative)
meine Schwester (my sister – feminine, nominative)
meine Schwestern (my sisters – plural, nominative)

Using mein Schwester would be grammatically wrong because the possessive doesn’t match the feminine noun in the nominative case.

Does Schwester here mean sister or nurse?

By default, Schwester means (female) sister in a family sense.

Historically and in some contexts, Schwester on its own could also mean nurse (like “sister” in a hospital, especially in older British English). But in modern standard German:

die Schwester → usually just sister
die Krankenschwester → (female) nurse (literally “sick-person sister”)
More modern neutral term: die Pflegekraft, die Pflegefachkraft

So in your sentence Meine Schwester arbeitet ehrenamtlich im Krankenhaus, the natural reading is:

My (actual) sister volunteers at the hospital.

If you specifically wanted to say she works as a nurse (profession), you’d normally be more explicit, for example:

Meine Schwester arbeitet als Krankenschwester im Krankenhaus.
My sister works as a nurse at the hospital.

Why is the verb arbeitet in second position? Isn’t it the third word?

German main clauses follow the V2 rule: the finite verb (here arbeitet) must be the second element in the sentence.

An “element” is not the same as a single word; it can be a whole phrase. In your sentence:

Meine Schwester → one complete subject phrase (1st element)
arbeitet → finite verb (2nd element – required by V2)
ehrenamtlich im Krankenhaus → everything else

So even though arbeitet is the second word, more importantly, it is the second sentence element, which is exactly what German word order requires in a main clause.

What exactly does ehrenamtlich mean? Is it just “for free”?

ehrenamtlich means doing work in an honorary or voluntary capacity, typically for a good cause, and usually within some kind of organization (club, charity, association, etc.). It strongly suggests:

The work is unpaid or only symbolically paid.
It is done for a cause or for the community, not for profit.
It is often part of an official role (an “honorary office”).

Compare:

ehrenamtlich – in an honorary/volunteer role, often organized (e.g. with the Red Cross, a sports club, a charity).
freiwillig – voluntary, of one’s own free will (can be broader; not always about organized volunteer work).
unbezahlt – unpaid, no money (neutral; could just be exploiting someone, not necessarily for a good cause).

In your sentence, arbeitet ehrenamtlich im Krankenhaus implies she volunteers there, in some organized way, not that she is simply “not getting paid” for normal work.

Can I change the word order and say Meine Schwester arbeitet im Krankenhaus ehrenamtlich?

Yes, that word order is grammatically correct.

Both of these are fine:

Meine Schwester arbeitet ehrenamtlich im Krankenhaus.
Meine Schwester arbeitet im Krankenhaus ehrenamtlich.

The difference is mainly emphasis and rhythm:

Version 1 (your original) puts a bit more focus on the type of work (voluntary) before saying where. It sounds very natural.
Version 2 places the location earlier and can be heard as emphasizing “it’s at the hospital that she does this voluntarily.”

German is relatively flexible with adverbs and prepositional phrases like ehrenamtlich and im Krankenhaus. The main thing is to keep the finite verb in second position, which both versions do.

Why is it im Krankenhaus and not in das Krankenhaus or ins Krankenhaus?

The preposition in in German can take either:

dative → for location (where something is)
accusative → for direction/motion (where something is going)

Here, arbeiten describes a location, not movement:

She works in the hospital (she is there while working).

So in must take the dative:

in dem Krankenhaus → dative neuter singular
This contracts to im Krankenhaus (very common and natural).

Compare:

Sie arbeitet im Krankenhaus.
She works in the hospital. (location → dative, im)
Sie geht ins Krankenhaus.
She goes to the hospital. (motion → accusative, in das → ins)

So in your sentence, im = in dem (dative), which is correct for a static location.

What case is Krankenhaus in here, and why?

In im Krankenhaus, Krankenhaus is in the dative case, neuter singular.

Reason:

The preposition in
- location (where?) requires dative.
das Krankenhaus is a neuter noun.
Neuter singular dative with in would normally be in dem Krankenhaus.
in dem is contracted to im in everyday German.

So:

Nominative: das Krankenhaus
Accusative: das Krankenhaus
Dative: dem Krankenhaus → im Krankenhaus (with in)

Why is Krankenhaus capitalized, but ehrenamtlich is not?

In German:

All nouns are capitalized. → Krankenhaus (hospital)
Adjectives and adverbs are not capitalized in ordinary usage. → ehrenamtlich

So:

das Krankenhaus – noun → capital letter
ehrenamtlich arbeiten – adjective used adverbially → lowercase

This rule applies even in the middle of a sentence and is a reliable clue for identifying nouns in written German.

How do you pronounce ehrenamtlich?

ehrenamtlich is pronounced approximately like:

IPA: [ˈeːʁənˌʔamtlɪç]

Syllables and stress:

EHR-en-amt-lich
Main stress on the first syllable (EHR-).
There is usually a small glottal stop (a tiny break) before -amt- because ehren and amtlich meet.

Details:

e at the start: long [eː], like in English “they” but without the “y” sound.
r is a German ʁ (back of the throat), especially in standard German.
amt: the m and t are both clearly pronounced.
Final -lich uses the “ich-sound” [ç], like the ch in ich, not like the German Bach.

Very roughly for an English speaker: “AY-ren-umt-likh” (but without an English r and with the soft German ch at the end).

Is ehrenamtlich an adjective or an adverb here?

Grammatically, ehrenamtlich is an adjective that is being used adverbially.

As an adjective (before a noun), it would change its ending:
- ein ehrenamtlicher Helfer – a volunteer helper (masc.)
- eine ehrenamtliche Tätigkeit – a voluntary activity (fem.)
In your sentence, it describes how she works (the manner of working), so it functions like an adverb:
- Sie arbeitet ehrenamtlich. – She works as a volunteer / in an honorary capacity.

In German, adjectives and adverbs often look the same, but we distinguish them by function in the sentence.

Why is the tense just simple present arbeitet and not something like “is working”?

German doesn’t normally have a special progressive form (“is working”) like English. The simple present in German can cover:

English simple present:
- Sie arbeitet ehrenamtlich im Krankenhaus.
  She works as a volunteer at the hospital. (regular/habitual)
English present progressive:
- Sie arbeitet gerade ehrenamtlich im Krankenhaus.
  She is (currently) volunteering at the hospital.
  (with gerade added to emphasize “right now”)

So Meine Schwester arbeitet ehrenamtlich im Krankenhaus usually means a general, ongoing situation: she regularly volunteers there, not just at this exact moment.

How would I negate the sentence: “My sister does not volunteer at the hospital”?

The standard negation uses nicht:

Meine Schwester arbeitet nicht ehrenamtlich im Krankenhaus.

Placement of nicht:

It usually comes before what you want to negate most directly.
Here, the main thing you’re negating is the whole verb phrase arbeitet ehrenamtlich im Krankenhaus, so nicht comes right after the verb:
- arbeitet nicht ehrenamtlich im Krankenhaus

You could also say, with a slightly different emphasis:

Meine Schwester arbeitet im Krankenhaus, aber nicht ehrenamtlich.
My sister works at the hospital, but not as a volunteer.

Here the contrast is clearly that she does work there, but it’s not voluntary.

Could I say Meine Schwester jobbt ehrenamtlich im Krankenhaus instead of arbeitet?

Normally, no. That would sound odd.

arbeiten is the neutral, standard verb for to work.
jobben is informal and means to have a (usually casual, paid) job, often part-time or student work.

Since ehrenamtlich implies voluntary / unpaid work for a cause, combining it with jobben (which suggests earning money) is a mismatch.

So you should say:

Meine Schwester arbeitet ehrenamtlich im Krankenhaus. ✅

Use jobben only where it’s clearly about a paid side job:

Meine Schwester jobbt im Krankenhaus.
My sister has a (paid) job at the hospital. (sounds like a casual/side job)