noun
1.
a. or water spinner : an aquatic European spider ( Argyoneta aquatica ) that constructs beneath the surface of the water a bell-shaped structure of silk which is open beneath and filled with air carried down by the spider in the form of small bubbles
b. : any of various spiders that habitually live on or about the water ; especially : a large American spider ( Dolomedes sexpunctatus ) that runs rapidly on the surface of water
2. : water mite