hairpin bend
noun🔊/ˌheəpɪn ˈbend/
🔊/ˌherpɪn ˈbend/
(British English) (North American English hairpin curve, hairpin turn)
(also hairpin British English, North American English)
a sharp U-shaped bend in a road, especially a mountain road （尤指山路的）急转弯