plane 1 (plān)
1. Mathematics A surface containing all the straight lines that connect any two points on it.
2. A flat or level surface.
3. A level of development, existence, or achievement: scholarship on a high plane.
4. An airplane or hydroplane.
5. A supporting surface of an airplane; an airfoil or wing.
1. Mathematics Of or being a figure lying in a plane: a plane curve.
2. Flat; level. See Synonyms at level.
[Latin plānum, flat surface, from neuter of plānus, flat; see pelə-2 in the Appendix of Indo-European roots. N., sense 4, short for AEROPLANE.]
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