Plane 

plane [ playn ]

noun  (plural planes)

Definition: 
1. flat surface: a flat or level surface
2. level of reality: a particular level of existence, mental activity, or achievement never felt he was on the same intellectual plane as the others
3. mathematics two-dimensional surface or space: a two-dimensional surface in which a straight line between any two points will lie wholly on that surface
4. aviation wing or hydrofoil: a flat surface that provides lift for an aircraft or hydroplane, e.g. a wing or a hydrofoil

adjective 

Definition: 
1. flat: flat or level
2. mathematics two-dimensional: lying within a plane

intransitive verb 

(3rd person present singular planes, present participle planing, past and past participle planed)
Definition: 
1. skim over surface of water: to rise partly out of water and skim along the surface
2. aviation birds glide: to glide through the air without propulsion

[Early 17th century. < Latin planus 'flat']
planeness noun

Regional History 
See plain.