terrain

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An area of land; ground: climbed a tree to view the surrounding terrain.
2. n. A particular geographic area; a region: a guide who knows this terrain well.
3. n. The surface features of an area of land; topography: boots designed for rugged terrain.
4. n. Variant of terrane.

Century Dictionary and Cyclopedia

1. n. A part of the earth's surface limited in extent; a region, district, or tract of land, either looked at in a general way or considered with reference to its fitness or use for some special purpose, as for a building-place or a battle-field: a term little used in English except in translating from the French, and then with the same meaning which it has in the original. The word is, however, also used in various idiomatic expressions, in translating a number of which the English word “ground” is most properly employed: as, “gagner du terrain,” to gain ground; “perdre du terrain,” to lose ground, favor, or credit; also with various metaphorical significations: as, “être sur son terrain,” to have to do with, or to speak of, that with which one is thoroughly familiar; “sonder le terrain,” examine the conditions, or look into the matter, etc. As used by French geologists, the word terrain has a somewhat vague meaning, and is usually limited by some qualifying term: as, “terrain de transition,” “terrain primitif.” This word was introduced into English geological literature by the translator of Humboldt's “Essai Géognostique,” where it was used, as he remarks, “because we have no word in the English language which will accurately express terrain as used in geology by the French.” Also spelled (but rarely) terrane.

Wiktionary

1. n. geology A single, distinctive rock formation; an area having a preponderance of a particular rock or group of rocks.
2. n. An area of land or the particular features of it.

WordNet 3.0

1. n. a piece of ground having specific characteristics or military potential