The Collaborative International Dictionary of English v.0.48:

Orthotomic \Or`tho*tom"ic\, a. [Ortho- + Gr. ? to cleave.]
   (Geom.)
   Cutting at right angles.
   [1913 Webster]

   Orthotomic circle (Geom.), that circle which cuts three
      given circles at right angles.
      [1913 Webster]