A more thorough explanation:

Definition: OS stands for Ordinary Seaman, which is a term used in maritime law to refer to a seaman who has some experience but is not proficient enough to be classified as an able-bodied seaman. An OS is attached to a navigating vessel as an employee below the rank of officer and contributes to the function of the vessel or the accomplishment of its mission.

For example, an OS may be responsible for cleaning and maintaining the vessel, assisting with navigation, and performing other duties as assigned by the captain or other officers. While an OS has some experience, they are not yet qualified to perform all seaman's duties and may require further training and experience to become an able-bodied seaman.

Seamen's injuries are covered under the Jones Act and the general maritime law, which provide remedies for seamen who are injured or killed in the course of their employment. However, determining who qualifies as a seaman under the Jones Act can be a complex legal issue, as the definition of a seaman has been subject to varying interpretations by the courts over time.