mountainous (adj.)

• abysmal
• alpestrine
• alpine
• astronomic
• astronomical
• awesome
• boundless
• bulky
• colossal
• cosmic
• craggy
• elephantine
• enormous
• epic
• extensive
• formidable
• galactic
• giant
• gigantic
• heroic
• high
• hilly
• huge
• immeasurable
• immense
• infinite
• jumbo
• king-size
• knobby
• large
• mammoth
• massive
• mighty
• monstrous
• monumental
• outsize
• overgrown
• prodigious
• profound
• rolling
• sizable
• spacious
• staggering
• steep
• stupendous
• subalpine
• titanic
• towering
• tremendous
• vast
• voluminous
• weighty