15c. metathesis of Middle English drit, drytt "mud, dirt, dung" (c.1300), from Old Norse drit, cognate with Old English dritan "to void excrement," from Proto-Germanic *dritanan (cf. Dutch drijten, Old High German trizan).
Used abusively of persons from c.1300. Meaning "gossip" first attested 1926 (in Hemingway); dirt bike is 1960s. Dirt-cheap is from 1821. Dirt road attested by 1852.