Slang. a person paid to carry or transport contraband, especially drugs, for a smuggler.
6.
a small locomotive used for pulling rail cars, as in a coal yard or on an industrial site, or for towing, as of ships through canal locks.
7.
Also called spinning mule. a machine for spinning cotton or other fibers into yarn and winding the yarn on spindles.
8.
Nautical. a large triangular staysail set between two masts and having its clew set well aft.
9.
Numismatics. a hybrid coin having the obverse of one issue and the reverse of the succeeding issue, or vice versa.
10.
Biology. a hybrid, especially one between the canary and some other finch.
Origin of mule1