Source : Webster's Revised Unabridged Dictionary (1913)

Plani- \Plan"i-\, Plano- \Plan"o-\ [L. planus. See {Plane}, a.]
   Combining forms signifying flat, level, plane; as
   planifolious, planimetry, plano-concave.

Plano- \Pla"no-\
   See {Plani-}.