sprock·et
noun/ˈsprɒkɪt/
/ˈsprɑːkɪt/
- (also sprocket wheel)a wheel with a row of teeth around the edge that connect with the holes of a bicycle chain or with holes in a film, etc. in order to turn it
链轮；输片齿轮 - one of the teeth on such a wheel
enlarge image链轮齿；链齿
Word Originmid 16th cent. (denoting a triangular piece of timber used in a roof): of unknown origin.