Plain or Plane?
Your choice!
Plain
Exemple : ‘’I prefer plain clothes over fancy ones.’’
The words "plain" and "plane" are homonyms and thus are often mixed up. The word "plain" is used as an adjective to denote something which is ordinary or not fancy. It is also used as a noun in order to denote a large area of flat land.
Plane
Exemple : ‘’I bought him a toy plane for his birthday.’’
The word "plane" is used as a shortening of the word "aeroplane." It can also be used to denote a particular level or particular standard.