dirt [ME] The origin of dirt is old Scandinavian drit ‘excrement’. In its earliest uses the English word retained both the meaning and the form, but gradually dirt superseded drit. Its history parallels that of *bird (earlier brid). Dirty is Late Middle English. The sense ‘obscene, pornographic, smutty’ dates from the 16th century, though most familiar phrases such as dirty joke and dirty weekend are first recorded in the 20th century.