The Collaborative International Dictionary
Trisecting
Trisect \Tri*sect"\, v. t. [imp. & p. p. Trisected; p. pr. & vb. n. Trisecting.] [Pref. tri- + L. sectus, p. p. of secare to cut. See Section.]
To cut or divide into three parts.
(Geom.) To cut or divide into three equal parts.
Wiktionary
trisecting
vb. (present participle of trisect English)