\Wa"ter spi"der\ (Zo["o]l.)
(a) An aquatic European spider ({Argyoneta aquatica}) which
    constructs its web beneath the surface of the water on
    water plants. It lives in a bell-shaped structure of
    silk, open beneath like a diving bell, and filled with
    air which the spider carries down in the form of small
    bubbles attached one at a time to the spinnerets and hind
    feet. Called also {diving spider}.
(b) A water mite.
(c) Any spider that habitually lives on or about the water,
    especially the large American species ({Dolomedes
    lanceolatus}) which runs rapidly on the surface of water;
    -- called also {raft spider}.