Terrain adjectives are listed in this post. Each word below can often be found in front of the noun terrain in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing TERRAIN.
alpine, arid, barren, beautiful, broken, bumpy, challenging, complex, complicated, conceptual, contested, covered, cultural, dangerous, different
difficult, digital, discursive, diverse, dry, easy, economic, emotional, entire, familiar, fertile, flat, foreign, forested, geographical
harsh, high, higher, hilly, historical, hostile, human, ideological, inhospitable, inner, intellectual, irregular, key, legal, like
local, marshy, moral, mountainous, muddy, natural, new, open, own, particular, physical, political, rocky, rolling, rough
rougher, rugged, same, sandy, similar, sloping, social, steep, such, super, surrounding, swampy, theoretical, tough, treacherous
uncertain, uncharted, undulating, uneven, unexplored, unfamiliar, unforgiving, unknown, urban, varied, vast, whole, wild, wooded
Hope this word list had the adjective used with terrain you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.