The Collaborative International Dictionary of English v.0.48:

Bisect \Bi*sect"\, v. t. [imp. & p. p. Bisected; p. pr. & vb.
   n. Bisecting.] [L. bis twice + secare, sectum, to cut.]
   1. To cut or divide into two parts.
      [1913 Webster]

   2. (Geom.) To divide into two equal parts.
      [1913 Webster]