A flat disk, as of metal, plastic, rubber, or leather, placed beneath a nut or bolt to make the connection more secure or distribute pressure or placed between parts to space the parts properly or prevent leakage in a joint, An annular piece of leather, rubber, metal, or other material placed at a joint in a water-pipe or faucet to make the joint tight and prevent leakage, or over a bolt, or a similar piece upon which a nut may be screwed, One who, or that which, washes