The term 'Cartoon Animator's Sheet' can be summarized as a three-letter acronym, CEL. This acronym stands for 'Cels, ' which are transparent sheets of celluloid used in traditional hand-drawn animation. The cels are painted on one side and placed over a background image to create the illusion of movement. Cels are an essential part of the animation process and are used to create the characters and backgrounds seen in cartoons.