(slang) Too irrational to be dealt with sanely.

(zoology) Any member of the family Asilidae of robber flies.

A wheel composed of an abrasive compound and used for various grinding and abrasive machining operations. / (figuratively, by extension) Something that wears down or harms by attrition.

(mining, historical) A miner who makes excavations in hard strata other than coal.