D defs.my
Entry 1 sense Webster, 1913

Water devil

/wôt'-ẽr dĕv'-əl/ · Wa·ter dev·il · IPA
01 The rapacious larva of a large water beetle (Hydrophilus piceus), and of other similar species. See Illust. of Water beetle.
  1. 1.
    The rapacious larva of a large water beetle (Hydrophilus piceus), and of other similar species. See Illust. of Water beetle.(Zool.)