moun ‧ tain ‧ ous /ˈmaʊntənəs, ˈmaʊntɪnəs $ ˈmaʊnt ə nəs/ BrE AmE adjective
1 . a mountainous area has a lot of mountains:
the mountainous coast of Wales
a mountainous region
2 . very large in amount or size SYN massive :
They were struggling with mountainous debts.