rǯm - to stone; II. to place a stone on one’s grave (Lane 1047)

See also Proto-MSA *rgm - to cover The reconstruction in HALOT 1187: “The basic meaning develops from ‘to heap up stones’ > ‘to stone’ > ‘to curse’ > ‘to make a statement’” appears highly improbable, especially in its latter step (“to curse” > “to make a statement”)