(~s)
1.
A ~ is a horse which is used to do a job, for example to pull a plough.
N-COUNT
2.
If you describe a person or a machine as a ~, you mean that they can be relied upon to do a large amount of work, especially work that is dull or routine.
...the Wellington bomber, the great ~ of the war...
My husband never even looked at me. I was just a ~ bringing up three children.
N-COUNT: usu with supp