/ təˈreɪn; NAmE / noun
[ C , U ] used to refer to an area of land when you are mentioning its natural features, for example, if it is rough, flat, etc. :
difficult / rough / mountainous, etc. terrain
➡ note at country
••
WORD ORIGIN
early 18th cent. (denoting part of the training ground in a riding school): from French , from a popular Latin variant of Latin terrenum , neuter of terrenus from terra earth.