job-horse—a horse hired to do a particular piece of work, or for a limited time:
- The sight of Dr. Slocum’s large carriage, with the gaunt job-horses, crushed Flora.
work horse—
1. a horse used for labor rather than for racing or recreation:
- Pink-eye is excessively prevalent among all classes of horses, particularly work horses in Sheffield.
2. a person who undertakes hard but necessary work:
- Rice-producing peasants continued to be the workhorses of the nation and the economic support of the ruling class.
3. a particularly useful or durable machine:
- This caliber howitzer has gained the reputation of being the “work horse” of the Army.