Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
Wiktionary
n. 1 A student athlete that wants to try out for a college sports/athletic team without the benefit of a scholarship or having been recruited. 2 An actor of a small (or "bit part") part in a theatrical production or film, often without speaking lines. 3 Such a part in a play or film. Usually as '''walk-on''' role or '''walk-on''' part.
WordNet
n. plays a small part in a dramatic production
adj. not capable of or especially not involving speech or spoken lines; "had a nonspeaking role in the play" [syn: nonspeaking] [ant: speaking(a)]
Wikipedia
The term walk-on is used in sports, particularly American college athletics, to describe an athlete who becomes part of a team without being actively recruited beforehand or awarded an athletic scholarship. This results in the differentiation between "walk-on" players and "scholarship" players.
Usage examples of "walk-on".
Stanislavski or summer stock or college theater under their belts, fueled by Oscar fantasies but settling, a thousand cattle calls later, for the occasional walk-ons and crowd scenes and nonunion commercials that comprised 99.
Manhattan groundlings, extras and understudies, walk-ons and bit-part players, these unknown Earthlings.
Up on the stage, what looked like a cross between the cast of Robin Hood and the cast of Riverdance with a few walk-ons from Braveheart thrown in were making an almighty Celtic racket.
He rides herd on everybody: director, principals, walk-ons, arrangers, musicians, everybody.
Given the pomp and posturing surrounding her, she felt like a walk-on in Noises Off.
I walked back to the hotel through the crowds (here they come again) of Manhattan groundlings, extras and understudies, walk-ons and bit-part players, these unknown Earthlings.
A pathetic rdsumd with a couple of commercials, a handful of walk-ons, and a Icad in a three-act play that closed in Pittsburgh on opening night.