Source : Webster's Revised Unabridged Dictionary (1913)

Fluidal \Flu"id*al\, a.
   Pertaining to a fluid, or to its flowing motion.

   {Fluidal structure} (Geol.), the structure characteristic of
      certain volcanic rocks in which the arrangement of the
      minute crystals shows the lines of flow of thew molten
      material before solidification; -- also called {fluxion
      structure}.