- abounding in mountains: a mountainous wilderness.
- of the nature of a mountain.
- resembling a mountain or mountains, as being very large and high: mountainous waves.
- of or relating to mountainsa mountainous region
- like a mountain, esp in size or impressiveness
adj.late 14c., from Old French montagneux, from Vulgar Latin *montaneosus “mountainous,” from *montanea (see mountain).