From mountain + -y.
mountainy (comparative more mountainy, superlative most mountainy)
- (now chiefly Ireland) Mountainous. [from 16th c.]
- 1925, Ford Madox Ford, No More Parades, Penguin 2012 (Parade's End), p. 292:
- His girl, who worked on a mountainy farm above Caerphilly, had written to him about a queer cow […].
- 2013, Molly Keane, Time After Time
- The mountainy fields rose quietly outside it towards gorse and heather.