rec·ti·lin·e·ar 
(rĕk′tə-lĭnē-ər)
(rĕk′tə-lĭnē-ər)adj.
Moving in, consisting of, bounded by, or characterized by a straight line or lines: following a rectilinear path; rectilinear patterns in wallpaper.
[From Late Latin rēctilīneus : Latin rēctus, right; see reg- in the Appendix of Indo-European roots + Latin līnea, line; see LINE1.]
rec′ti·line·ar·ly adv.