S: (n) straight line (a line traced by a point traveling in a constant direction; a line of zero curvature) "the shortest distance between two points is a straight line"
S: (adj) oblique (slanting or inclined in direction or course or position--neither parallel nor perpendicular nor right-angled) "the oblique rays of the winter sun"; "acute and obtuse angles are oblique angles"; "the axis of an oblique cone is not perpendicular to its base"