If "plane" refers to a flat surface:
* Curved: A surface that is not flat.
* Uneven: A surface that is not smooth or level.
* Three-dimensional: A space with length, width, and height.
If "plane" refers to an aircraft:
* Ship: A water-based vessel.
* Train: A land-based vehicle running on rails.
* Car: A land-based vehicle with wheels.
* Helicopter: An aircraft that uses rotating blades for flight.
If "plane" refers to a mathematical concept:
* Solid: A three-dimensional object.
* Curve: A line that is not straight.
Please provide more context for a more specific antonym.