(~s)
1.
Something that serves as a ~ of another thing makes you think about the other thing. (WRITTEN)
The British are about to be given a sharp ~ of what fighting abroad really means...
N-COUNT: usu sing, oft N of n/wh, N that
2.
A ~ is a letter or note that is sent to tell you that you have not done something such as pay a bill or return library books. (mainly BRIT)
...the final ~ for the gas bill.
N-COUNT