Trilateral \Tri*lat"er*al\, a.[L. trilaterus; tri- (see {Tri-})
+ latus, lateris, side: cf. F. trilat['e]ral. See {Lateral}.]
(Geom.)
Having three sides; being three-sided; as, a trilateral
triangle. -- {Tri*lat"er*al*ly}, adv. --
{Tri*lat"er*al*ness}, n.
[1913 Webster]