English
planation
From plane + -ation.
Formed from plane + -ation
Proto-Indo-European *pleh₂- ‘flat’
Proto-Indo-European *pl̥h₂nós
Proto-Italic *plānos
Latin plānus ‘plain’
Latin plānum ‘flat surface’
English plane
Today it means
noun The formation of a flat surface by erosion and deposition
Language periods are conventional ranges, not dates for this word.
Etymograph / planation