\La"va\, n. [It. lava lava, orig. in Naples, a torrent of
rain overflowing the streets, fr. It. & L. lavare to wash.
See {Lave}.]
The melted rock ejected by a volcano from its top or fissured
sides. It flows out in streams sometimes miles in length. It
also issues from fissures in the earth's surface, and forms
beds covering many square miles, as in the Northwestern
United States.
Note: Lavas are classed, according to their structure, as
      scoriaceous or cellular, glassy, stony, etc., and
      according to the material of which they consist, as
      doleritic, trachytic, etc.
{Lava millstone}, a hard and coarse basaltic millstone from
   the neighborhood of the Rhine.
{Lava ware}, a kind of cheap pottery made of iron slag cast
   into tiles, urns, table tops, etc., resembling lava in
   appearance.