geological formation, formation - (geology) the geological features of the earth

highland, upland - elevated (e.g., mountainous) land

hill - a local and well-defined elevation of the land

hills - hilly land; "they loved to roam the hills of West Virginia"; "the Black Hills"

mountain, mount - a land mass that projects well above its surroundings; higher than a hill

foreland, headland, promontory - a natural elevation (especially a rocky one that juts out into the sea)

ridge - a long narrow natural elevation or striation

incline, slope, side - an elevated geological formation; "he climbed the steep slope"; "the house was built on the side of the mountain"

swell - a rounded elevation (especially one on an ocean floor)