Perpendicular- At an angle of 90° to a given line (or plane or surface).
Purple dictionary (perpendicular) sat on the book shelf at 90° angle.
Purple dictionary is perpendicular to the book shelf.
The towers are perpendicular to the road of the bridge.
Although the blue line is on an incline, the red line is still at 90° to it and so is perpendicular to the blue line.
The sides of a cube are perpendicular to each adjoining side.
Railway sleepers are laid perpendicular to the track.