blind alley

Từ điển Oxford Advanced Learner 8th

ˌblind ˈalley [blind alley] BrE NAmE noun
a way of doing sth that seems useful at first, but does not produce useful results, like following a path that suddenly stops
•Progress in science cannot be made without exploring blind alleys.

• Từ đồng nghĩa / Synonyms:
  cul de sac, dead-end street, impasse