a piece of ground having specific characteristics or military potential
"they decided to attack across the rocky terrain"
A single, distinctive rock formation; an area having a preponderance of a particular rock or group of rocks.
"The hikers paused to examine the ancient terrain where massive granite boulders dominated the landscape."
In plain English: Terrain is the natural features of an area, such as hills and valleys, that make up its surface.
"The hikers struggled through the rocky terrain to reach the summit."
Usage: Use terrain to describe the physical characteristics and surface features of land rather than specific geological formations like individual rocks. This word is best applied when discussing how the landscape affects movement, travel, or military strategy in an area.
The word terrain entered English directly from French without being adapted to fit English spelling rules. It ultimately traces back to the Latin word for "earth," originally describing land or ground made up of soil.