outside lane
noun/ˌaʊtsaɪd ˈleɪn/
/ˌaʊtsaɪd ˈleɪn/
(British English) (North American English passing lane)
- the part of a major road such as a motorway or interstate nearest the middle of the road, where vehicles drive fastest and can go past vehicles ahead
（高速公路等靠近路中心的）外车道，超车道