Source : Webster's Revised Unabridged Dictionary (1913)

Subcostal \Sub*cos"tal\, a. (Anat. & Zo["o]l.)
   Situated below the costas, or ribs; as, the subcostal
   muscles.

   Note: The subcostal muscles are distinct from, and within,
         the intercostal.

Subcostal \Sub*cos"tal\, n.
   1. (Anat.) A subcostal muscle.

   2. (Zo["o]l.) One of the principal nervures of the wings of
      an insect. It is situated next beneath or behind the
      costal. See {Nervure}.