As an adjective hilly
is (of a landscape) abundant in hills; having many hills.
As a noun hillwalking is
(british|irish) a pastime of walking in hilly countryside.
hilly
English
Adjective
(er)
(of a landscape) Abundant in hills; having many hills.
hillwalking
Noun
(-)
(British, Irish) A pastime of walking in hilly countryside.
See also
* fellwalking