noun
dead end; end of the line
Refers to a physical dead end, or metaphorically to a situation with no way forward.
この道はどん詰まりだから、引き返そう。
This road is a dead end, so let's turn back.
交渉はどん詰まりに達した。
The negotiations reached a dead end.
行き止まり is a more standard and neutral term for a dead end, while どん詰まり is more colloquial and emphatic.
The prefix どん- is an intensifier, and 詰まり comes from the verb 詰まる (to be blocked). The exact origin of どん is uncertain, but it may be related to onomatopoeic or emphatic elements.