A metal spike with a hole for a rope; mountaineers drive it into ice or rock to use as a hold WordNet 3.0 & Open English WordNet

A piton in big wall climbing and in aid climbing is a metal spike that is driven into a crack or seam in the climbing surface using a climbing hammer, and which acts as an anchor for protecting the climber against the consequences of falling or to assist progress in aid climbing. Wikipedia

A metal spike to aid climbing Wikipedia Disambiguation

Rock climbing tool. Wikipedia Disambiguation

A spike, wedge, or peg that is driven into a rock or ice surface as a support (as for a mountain climber). Wiktionary

A spike, wedge, or peg (climbing). Wiktionary (translation)