■ noun
1》 a classification or ranking based on quality, standard, or performance.
↘the value of a property or condition which is claimed to be standard, optimal, or limiting for a material, device, etc.: a low octane ~.
↘any of the classes into which racing yachts are assigned according to dimensions.
2》 ( ~s ) the estimated audience size of a television or radio programme.
3》 Brit. a non-commissioned sailor in the navy. [from the position or ~ held by a sailor, recorded on a ship's books.]