mountain (n.) Look up mountain at Dictionary.com
c.1200, from Old French montaigne (Modern French montagne), from Vulgar Latin *montanea "mountain, mountain region," noun use of fem. of *montaneus "of a mountain, mountainous," from Latin montanus "mountainous, of mountains," from mons (genitive montis) "mountain" (see mount (n.)).

Until 18c., applied to a fairly low elevation if it was prominent (such as Sussex Downs, the hills around Paris). As an adjective from late 14c. Mountain dew "raw and inferior whiskey" first recorded 1839; earlier a type of Scotch whiskey (1816); Jamieson's 1825 "Supplement" to his Scottish dictionary defines it specifically as "A cant term for Highland whisky that has paid no duty." Mountain-climber recorded from 1839; mountain-climbing from 1836.