The crossword solution for the term PLAIN, SAY is TERRAIN. A plain is a flat, wide area of land with few trees and little change in elevation. Plains are often found in grasslands, deserts, and near rivers and lakes. They are also known as lowlands or plateaus. Plains are usually covered with grasses, shrubs, and other vegetation. The word TERRAIN is derived from the Latin terra, meaning 'EARTH'. It is used to describe the physical features of an area, such as its topography, soil, and vegetation.