Source : Webster's Revised Unabridged Dictionary (1913)

Pyramidic \Pyr`a*mid"ic\, Pyramidical \Pyr`a*mid"ic*al\, a.
   Of or pertaining to a pyramid; having the form of a pyramid;
   pyramidal. `` A pyramidical rock.'' --Goldsmith. ``Gold in
   pyramidic plenty piled.'' --Shenstone. --
   {Pyr`a*mid"ic*al*ly}, adv. {Pyr`a*mild"ic*al*ness}, n.

Source : WordNet®

pyramidically
     adv : in a pyramidal manner or shape; "the bush was trimmed
           pyramidically"