mule

One day he ran into a herd of a half dozen elk, so he rode his mule down the canyon three or four miles, leaving the sheep alone.

It would be exceedingly interesting to know if the hybrid would reproduce, a matter I deem exceedingly doubtful, for the chances are it would prove a "mule" (infertile).

Vegetable mules supply an irrefragable argument in favour of the sexual system of botany.

Where in the hell do you think I learned to be such a mule?

“Yeah, in Denver, we know about Uriarte's involvement in meth. Our Las Cruces office seized over six hundred pounds of methamphetamine from two of his mules last year.”

What is less clear, however, is why mint workers should have chosen to produce mules, if they were making forgeries […]

He was in the middle of organizing his massive stash of rare and exquisite bounty, all kept safely in the inventory cache of a mule, an entirely separate character which he paid a monthly fee to maintain exclusively for that purpose.

In heavier seas where a boat must sail a course dictated by waves, or where wave action makes power more important than pointing, the mule will prove the faster sail.