means The activity of climbing mountains, especially the technical, high-altitude kind that demands ropes, ice axes, and a tolerance for thin air and worse weather.

from Built from "mountain" plus the suffix "-eer" (one who deals with a thing, as in "engineer" or "pioneer"), then verbed into "-eering." "Mountain" itself climbs back through Old French "montaigne" to Latin "mons, montis," a hill or mountain. The word emerged as a proper pursuit in the 19th century, when European Alpinists turned scrambling up peaks from a peasant's necessity into a gentleman's obsession.