The phrase "film debut" refers to someone or something appearing or being shown for the first time in a movie. It is the first time that a particular person or thing becomes known to the public through the medium of film. Full definition
Mostly known as a character actor and supporting player, he first appeared on television in 1954 and made his feature film debut in 1957, going on to more than 200 screen credits. (latimes.com)
Being able to attend film festivals, one is prone to see several feature film debuts by promising filmmakers. (flickeringmyth.com)
Without anything to model itself after, the 1979 film debut does an incredible job of blazing new trails. (dvdizzy.com)