STEP Hebrew Lexicon: כָּבַס

1) to wash (by treading), be washed, perform the work of a fuller

1a) (Qal) washer, fuller, treader (participle)

1b) (Piel) to wash (garments, person)

1c) (Pual) to be washed

1d) (Hothpael) to be washed out