n.
Function: noun
Etymology: Latin planum, from neuter of planus level
Date: 1571
1 a : a surface in which if any two points are chosen a straight line joining them lies wholly in that surface b : a flat or level surface
2 : a level of existence, consciousness, or development <on the intellectual plane >
3 a : one of the main supporting surfaces of an airplane b [by shortening] : AIRPLANE