Rectilineal \Rec`ti*lin"e*al\ (-l?n"?*al), Rectilinear \Rec`ti*lin"e*ar\ (-l?n"?*?r), a. [Recti- + lineal, linear.]

Straight; consisting of a straight line or lines; bounded by straight lines; as, a rectineal angle; a rectilinear figure or course. -- Rec`ti*lin"e*al*ly, adv. -- Rec`ti*lin"e*ar*ly, adv.

Source: Webster's Revised Unabridged Dictionary (1913)