sheriff: [OE] A sheriff is etymologically a ‘shirereeve’ – that is, a ‘county official’. The term was compounded in the Old English period from scīr, ancestor of modern English shire, and gerēfa ‘local official’, a word based on *rōf ‘assembly’ which survives as the historical term reeve. It was used for the ‘monarch’s representative in a county’. => reeve, shire
sheriff (n.)
late Old English scirgerefa "representative of royal authority in a shire," from scir (see shire) + gerefa "chief, official, reeve" (see reeve). As an American county official, attested from 1660s; sheriff's sale first recorded 1798. Sheriff's tooth (late 14c.) was a common name for the annual tax levied to pay for the sheriff's victuals during court sessions.