slasher (n.)

1540s, intransitive, "to make cuts or cutting motions with a stroke of a blade or whip;" 1580s, transitive, "cut with long incisions;" perhaps from French esclachier "to break," variant of esclater "to break, splinter" (see slat).

Attested from 1650s as "to strike violently or at random." The meaning "to clear land" (of trees) is from 1821, American English. In reference to prices, "reduce severely," it is attested by 1876 in U.S. newspaper advertisements. Related: Slashed; slashing. Slash and burn for a method of clearing forest for cultivation is by 1887.