n.1 a a person or thing that washes. b a washing-machine.
2 a flat ring of rubber, metal, leather, etc., inserted at a joint to tighten it and prevent leakage.
3 a similar ring placed under the head of a screw, bolt, etc., or under a nut, to disperse its pressure.
4 Austral. a cloth for washing the face.
Phrases and idioms:
washer-up (pl. washers-up) a person who washes up dishes etc.