What is telecine judder?

Some articles on telecine judder, telecine:

Television Standards Conversion - Role of Information Theory - Telecine Judder
... conversion process for 24 frame/s film to television (telecine) creates a slight error in the video signal compared to the original film frames ... This process is commonly referred to as telecine judder ... similar lack of smoothness, though this effect is not usually called “telecine judder” ...