Brown Driver Briggs

 1. to cover, purge, make an atonement, make reconciliation, cover
over with pitch
  1) (Qal) to coat or cover with pitch
  2) (Piel)
1b1. to cover over, pacify, propitiate
1b2. to cover over, atone for sin, make atonement for
1b3. to cover over, atone for sin and persons by legal rites
  3) (Pual)
1c1. to be covered over
1c2. to make atonement for
  4) (Hithpael) to be covered