A list of duties in an organisation, school, club, flatshare, etc.
Have you got the roster for this month? Who’s responsible for cleaning the kitchen? They look like they haven’t been touched.
Or the schedule for different posts in an organisation like a hospital. We can see it used as a verb here.
I’m rostered on for nights next week but then I have four days off straight so I guess that’s something.
According to the roster, I am on front desk until 11 when Stuart comes to relieve me.
In American English schedule or rota may replace this word.
What is interesting is that roster comes to English from Dutch and is derived from the word roast.
Apparently someone made a connection between the straight lines of the grid or grill and a list of duties. Or maybe they thought that being rostered on to something was like having a hot iron applied. Go figure!