英语词源字典 - 在线词源网站

Montana [Montana 词源字典]: U.S. state, from Latinized form of Spanish montaña "mountain," from Latin mont-, stem of mons (see mountain). Proposed 1864 by U.S. Rep. James H. Ashley of Ohio when it was created as a territory from Nebraska Territory, in reference to the Rocky Mountains, which however traverse only one end of it. Admitted as a state 1889. Related: Montanan.[Montana etymology, Montana origin, 英语词源]
Rockies (n.): "the Rocky Mountains," 1827; see rocky.
rocky (adj.): "full of rocks," c. 1400, from rock (n.1) + -y (2); "unsteady," 1737, from rock (v.1). Meaning "difficult, hard" is recorded from 1873, and may represent a bit of both.

The Rocky Mountains so called by 1802, translating French Montagnes Rocheuses, first applied to the Canadian Rockies. "The name is not directly self-descriptive but is an approximate translation of the name of the former Native American people here known as the Assiniboin .... The mountains are in fact not noticeably rocky" [Room]. Bright notes that "These Indians were called /assiniipwaan/, lit. 'stone Sioux', by their Cree (Algonkian) neighbors".