Learn Hardcore German: Mein Freund hat einen Gips am Bein.

The basic (nominative) form is ein Gips (masculine).
After the verb haben, the thing you “have” is in the accusative case (direct object).
Masculine ein changes to einen in the accusative:
Nominative: ein Gips (A cast is …)
Accusative: einen Gips (He has a cast.)

So hat einen Gips = “has a cast.”

What gender is Gips, and is that always the case?

Gips is masculine: der Gips.

Singular: der Gips, einen Gips, dem Gips …
Plural (rare in this meaning): die Gipse.

For a medical cast, Germans essentially always treat Gips as masculine. You don’t need to worry about alternative genders here; standard German uses der Gips.

What exactly does am in am Bein mean?

am is a contraction of an dem.

an = “at / on (vertically, attached to)”
dem = dative singular of der (for masculine and neuter nouns)

So:

an dem Bein → am Bein

Grammatically, Bein is in the dative case after an here, because we’re talking about location, not movement. Literally: “a cast at the leg.”

Why is it am Bein instead of auf dem Bein?

In German, an is the natural preposition for something attached to a body part, and Gips am Bein haben is an idiomatic set phrase.

an (+ dative for position) = at / on / attached to
- einen Ring an der Hand haben – to have a ring on one’s hand
- eine Uhr am Handgelenk tragen – to wear a watch on one’s wrist
- einen Gips am Bein haben – to have a cast on one’s leg

auf dem Bein would literally be “on top of the leg” and sounds wrong for a cast; a cast surrounds and is attached to the leg, so an (→ am) is used.

Why is it am Bein (dative) and not ans Bein (accusative)?

With an, German distinguishes between:

Dative = location (where something is)
Accusative = direction/movement (where something is going)

In the sentence, the cast is already there; we’re describing a state:

am Bein = an dem Bein (dative) → “on/at the leg” (no movement)

If you were describing putting the cast onto the leg, you might use:

einen Gips ans Bein legen/anlegen = an das Bein (accusative, direction)

So am Bein is correct because it’s a static situation, not motion toward the leg.

Why doesn’t German say an seinem Bein like English “on his leg”?

German very often uses the definite article (der/die/das) with body parts instead of a possessive pronoun, especially when the owner is clear from context.

English: “My friend has a cast on his leg.”
Natural German: Mein Freund hat einen Gips am Bein.
Less common but correct: Mein Freund hat einen Gips an seinem Bein.

Because we already know we’re talking about mein Freund, it’s obvious whose leg it is. So German just says am Bein, not an seinem Bein. This pattern appears a lot:

Er hat sich die Hand gebrochen. – He broke his hand.
Sie putzt sich die Zähne. – She brushes her teeth.

Could I also say Mein Freund hat ein Gipsbein instead of … einen Gips am Bein?

You can see or hear Gipsbein, but it’s less neutral and slightly different in nuance.

einen Gips am Bein haben – standard, neutral way to say “have a cast on (one’s) leg.”
ein Gipsbein haben – literally “to have a plaster leg”; sounds more like describing the whole leg as a ‘plaster leg’, or joking/exaggerated/colloquial.

In ordinary conversation about someone who just broke their leg, einen Gips am Bein haben is the normal phrasing.

Does Bein mean “bone”? It looks like the English word “bone.”

No. Bein in modern German means leg (and sometimes “leg” of an animal or a piece of furniture).

das Bein = the leg
der Knochen = the bone

It’s a common false friend for English speakers. Some related words:

Beinbruch – broken leg (literally “leg-break”)
Knochenbruch – bone fracture

So in the sentence, Bein = “leg,” not “bone.”

Can Freund mean both “friend” and “boyfriend” here?

Yes. Freund is ambiguous and can mean:

friend (male friend)
boyfriend (romantic partner)

Context usually makes it clear. If you want to be more specific:

mein Freund – could be friend or boyfriend
mein Kumpel / mein Kollege – clearly just a buddy/colleague
mein fester Freund / mein Partner – clearly romantic

In isolation, Mein Freund hat einen Gips am Bein could mean either “My (male) friend…” or “My boyfriend…”, depending on context.

Is Gips the material (plaster) or the cast itself?

In everyday medical context, Gips can mean both:

The material (plaster of Paris):
- Gips anrühren – to mix plaster
The cast made from it:
- einen Gips am Bein haben – to have a plaster cast on one’s leg

In the sentence, it clearly means the cast. If you want to be more explicit, you can say:

Gipsverband – plaster cast (more technical)
Gips am Bein – the usual everyday way to say someone has a cast.