walk-in

[Mark A. Mandel]

Apropos the assertion in this weekend's On Language column, "a walk-in is
spookspeak for an unexpected defector or is a decorator's favorite closet":

You don't have to drop in on the folks at No Such Agency or The Company, or
pay an unexpected visit to a decorators' showroom, to be or see a walk-in.
Just stroll down the street to a nail salon or a beauty or barber shop that
announces "WALK-INS WELCOME" (with several possible variations on
punctuation that are beside the point here), and ask for service without an
appointment.

OED doesn't recognize this sense, but it's hardly obscure, and it's more
likely than the spookspeak to be known to the man or woman in the street.
Merriam-Webster Online has it:
   3 a : being a person who walks in without an appointment <a walk-in blood
   donor> b : of or relating to such persons <walk-in clinic>
So does American Heritage 4:
   3. Slang a. One who walks in without having an appointment.

-- Mark A. Mandel
Linguistic Data Consortium, University of Pennsylvania
[This text prepared with Dragon NaturallySpeaking.]