"agricultural implement, heavy wooden rake," c.1300, haru, from O.E. *hearwa, apparently related to O.N. harfr "harrow," and perhaps connected with O.H.G. herbist "harvest" (see harvest). Also possibly from hergian (see harry).
especially in harrowing of Hell in Christian theology, from hergian (see harry). In the figurative sense of "to wound the feelings, distress greatly" it is first attested c.1600 in Shakespeare.