1N-COUNT 役马;耕马 A workhorse is a horse which is used to do a job, for example to pull a plough. 役马;耕马
2N-COUNT 吃苦耐劳的人;老黄牛;重负荷机器 If you describe a person or a machine as a workhorse, you mean that they can be relied upon to do a large amount of work, especially work that is dull or routine. 吃苦耐劳的人;老黄牛;重负荷机器
...the Wellington bomber, the great workhorse of the war. [+ of]
在战争中立下汗马功劳的威灵顿轰炸机
My husband never even looked at me. I was just a workhorse bringing up three children.