|Definition - A thought expressed using several metaphors whose combined sense is illogical.|
Example - Rising above it all, he grabbed the bull by the horns and swept it under the rug.
Oxford English Dictionary - The term's first citation is from 1824:
"We should avoid making two inconsistent metaphors meet on one object. This is what is called mixed metaphor."
(L. Murray Eng. Gram. (ed. 5) I. 493)