n.

person who walks in without having an appointment

"the emergency room was overrun with walk-ins"

an operative who initiates his own defection (usually to a hostile country) for political asylum

an assured victory (especially in an election)

同義詞：waltz

a small room large enough to admit entrance

1. The doctor accepts walk-in patients every Wednesday afternoon.
   這位醫(yī)生每周三下午接受不預約的患者。
2. The restaurant has a walk-in policy, so you can come anytime without a reservation.
   這家餐廳有不預約的政策，所以你可以隨時來，不需要預定。