1. [mid-19C+] a period of work, usu. one that is physically demanding or unpleasant.
2. [late 19C–1900s] any period spent within an institution, e.g. a hospital.
3. [late 19C+] (US) a prison sentence.
4. [1900s–50s] (US) a term of service, e.g. in the army, on a ship.
5. [1910s] a situation one dislikes.
6. [1920s] an organization.