Source : Webster's Revised Unabridged Dictionary (1913)

Cacuminal \Ca*cu"mi*nal\, a. [L. cacumen, cacuminis, the top,
   point.] (Philol.)
   Pertaining to the top of the palate; cerebral; -- applied to
   certain consonants; as, cacuminal (or cerebral) letters.

Source : WordNet®

cacuminal
     adj : pronounced with the tip of the tongue turned back toward the
           hard palate [syn: {retroflex}]