die Sackgasse
dead-end street
A street that has only one entrance and is closed at the other end, so you have to turn around.
Wir sind aus Versehen in eine Sackgasse gefahren.
We accidentally drove into a dead-end street.

dead end
Loading your saved state.
dead-end street
A street that has only one entrance and is closed at the other end, so you have to turn around.
Wir sind aus Versehen in eine Sackgasse gefahren.
We accidentally drove into a dead-end street.

The word is made up of 'Sack' (sack) and 'Gasse' (alley/lane). Imagine an alley that, like a sack, has only one opening and is closed at the end. This image helps you remember the meaning easily.
Achtung, diese Straße ist eine Sackgasse, du musst hier wenden.
Careful, this street is a dead end; you have to turn around here.
The preposition 'in' is used with the dative or accusative depending on the situation. 'In einer Sackgasse sein/stecken' (to be/be stuck in a dead end; dative) describes the state, while 'in eine Sackgasse fahren/geraten' (to drive/end up in a dead end; accusative) describes movement toward it.
Wir stecken mit dem Auto in einer engen Sackgasse.
We are stuck with the car in a narrow dead-end street.
The figurative meaning 'ausweglose Situation' (hopeless situation) is a direct metaphor of a road with no way out. You can recognize it when the context is not about a real street, but about abstract things such as negotiations, discussions, or projects.
Die Diskussion über das neue Gesetz ist in einer Sackgasse gelandet.
The discussion about the new law has ended up in a dead end.
In the figurative meaning, 'Sackgasse' (dead end) is often combined with the verbs 'stecken' (to be stuck), 'sich befinden' (to be located / to find oneself), or 'geraten' (to end up).
Ich fühle mich in meinem Job in einer Sackgasse.
I feel like I'm in a dead end in my job.
trap
'die Falle' and 'die Sackgasse' can both describe a difficult situation that is hard to get out of. 'Falle' often sounds as if someone deliberately prepared the situation or deceived someone. 'Sackgasse' more often means that there is no longer any progress or solution. No one has to be at fault. Learners may confuse the words because both are used figuratively for a problem with no easy way out. If deception is important, 'Falle' fits; if a plan is not moving forward, 'Sackgasse' fits better.

Nach drei erfolglosen Versuchen war das Projekt in einer Sackgasse.
After three unsuccessful attempts, the project was at a dead end.
Beim Gespräch merkte Lisa zu spät, dass sie in eine Falle geraten war.
During the conversation, Lisa realized too late that she had fallen into a trap.