This term has two descriptions:
1) As movies are normally shot using 24.00fps framerate and American TV system, NTSC, uses framerate of 29.97fps, movie framerates need to be changed in order to get them play smoothly on TV.
This process, where studios add additional frames to the picture in order to increase the framerate, is called telecine. Process where various video editing tools reverse this process is called inverse telecine.
Technical details will be added later on.
2) Telecine also means a method to make an illegal bootleg copy of an original movie. Telecine method can be done in various ways, but normally it includes process where the movie is taken directly from the reel to digital format and then encoded into DVD-R, VCD, SVCD, DivX or XviD format. Other bootleg methods include Telesync, Screener, Cam and DVD-Rip.