A Quick and Simple Dictionary

walk-in

1. Adjective.  (context, of a place) that people may enter without a prior appointment.
2. Adjective.  (context, of a thief) that gains access through unlocked doors.
3. Adjective.  (context, of a defector etc) that walks into an embassy etc unannounced.
4. Adjective.  (US, of a cinema) not a drive-in.
5. Adjective.  (context, of a room) entered without an intervening passage.
6. Noun.  a walk-in room or closet.
7. Noun.  a walk-in defector etc.
8. Noun.  (parapsychology) A person whose original soul has departed the body and been replaced with another.
9. Noun.  A customer who visits a restaurant without a reservation.