dirtn.[OE. drit; kin to Icel. drit excrement, drta to dung, OD. drijten to dung, AS. gedrtan.]1. Any foul of filthy substance, as excrement, mud, dust, etc.; whatever, adhering to anything, renders it foul or unclean; earth; as, a wagonload of dirt.()Whose waters cast up mire and dirt. (Is. lvii. 20.)2. Meanness; sordidness.()Honors . . . thrown away upon dirt and infamy. (Melmoth.)3. In placer mining, earth, gravel, etc., before washing.()Dirt bed (Geom.), a layer of clayey earth forming a stratum in a geological formation. Dirt beds are common among the coal measures. -- Dirt eating. (a) The use of certain kinds of clay for food, existing among some tribes of Indians; geophagism. Humboldt. (b) (Med.) Same as Chthonophagia. -- Dirt pie, clay or mud molded by children in imitation of pastry. Otway (1684). -- To eat dirt, to submit in a meanly humble manner to insults; to eat humble pie.()v. t. To make foul of filthy; to dirty.(Swift.)