'Mountaineer' definitions:

Definition of 'mountaineer'

Someone who climbs mountains [syn: mountaineer, mountain climber]

Climb mountains for pleasure as a sport

From: GCIDE

Mountaineer \Moun`tain*eer"\ (moun`t[i^]n*[=e]r"), n. [OF. montanier, LL. montanarius. See Mountain.]
1. An inhabitant of a mountain; one who lives among mountains. [1913 Webster]
2. A rude, fierce person. [Obs.] [1913 Webster]
No savage fierce, bandit, or mountaineer. --Milton. [1913 Webster]
3. A person who climbs mountains for sport. [PJC]

From: GCIDE

mountaineer \moun`tain*eer"\, v. i. To live or act as a mountaineer; to climb mountains. [1913 Webster]
You can't go mountaineering in a flat country. --H. James. [1913 Webster]