From Longman Dictionary of Contemporary Englishsprocketsprock‧et /ˈsprɒkɪt $ ˈsprɑː-/ noun [countable] 1 
(also sprocket wheel)T a wheel with teeth (=parts along the edge) that fit into and turn a bicycle chain, a photographic film with holes etc2 Tone of the teeth on a sprocket wheel
(also sprocket wheel)T a wheel with teeth (=parts along the edge) that fit into and turn a bicycle chain, a photographic film with holes etc2 Tone of the teeth on a sprocket wheelExamples from the Corpus
sprocket• You must have a sprocket loose.• If you use continuous stationery, please remove sprocket margins and separate the sheets clearly into individual documents for each employee.• Picture, for example, a bicycle pedal as it turns round the sprocket. 