der Untermieter
subtenant
A person who rents part of an apartment or a room not from the owner, but from the main tenant.
Der neue Untermieter zieht nächste Woche in das freie Zimmer ein.
The new subtenant is moving into the empty room next week.

subtenant
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subtenant
A person who rents part of an apartment or a room not from the owner, but from the main tenant.
Der neue Untermieter zieht nächste Woche in das freie Zimmer ein.
The new subtenant is moving into the empty room next week.

The word is made up of 'unter' (under) and 'Mieter' (tenant). So a 'Untermieter' (subtenant) is literally a person who stands 'under' the main tenant in the rental hierarchy and rents from them.
Als Student hat er lange als Untermieter in einer WG gewohnt.
As a student, he lived for a long time as a subtenant in a shared apartment.
A 'Untermieter' (subtenant) rents from a 'Hauptmieter' (main tenant). The 'Hauptmieter' in turn rents the apartment from the 'Vermieter' (landlord/owner). So the word describes a specific position in a rental chain.
Der Hauptmieter muss den Vermieter um Erlaubnis fragen, bevor er einen Untermieter aufnimmt.
The main tenant must ask the landlord for permission before taking in a subtenant.
Common verbs used in connection with this word are 'einen Untermieter suchen' (to look for a subtenant), 'einen Untermieter aufnehmen' (to take in a subtenant), or 'als Untermieter wohnen' (to live as a subtenant).
Wir suchen einen neuen Untermieter für das freie Zimmer.
We are looking for a new subtenant for the empty room.
tenant
'Mieter' and 'Untermieter' both refer to people who pay rent for living space or rooms. The important difference is who they pay and whom they rent the space from. A Mieter rents directly from the owner or landlord. An Untermieter, on the other hand, rents from a main tenant, for example just one room in that person's apartment. Learners may confuse the words because both can live in a rented apartment. To be precise: the Mieter has the rental contract with the landlord, while the Untermieter has the contract with the main tenant.

Lena gibt dem Untermieter abends den Schlüssel für das freie Zimmer.
In the evening, Lena gives the subtenant the key to the spare room.
Nach dem Essen hat sie mit dem Mieter über die kaputte Heizung gesprochen.
After dinner, she talked to the tenant about the broken heating.