Plane figures are shapes that can be drawn on a flat surface, such as a piece of paper. The crossword solutions for the term 'plane figures' are ETAS (4 letters), COPILOT (7 letters), and COPILOTS (8 letters). ETAS stands for Ellipse, Triangle, Angle, and Square, which are all basic plane figures. A copilot is a person who assists the pilot in flying an aircraft, and copilots are multiple people who serve in this role.