Glossary of Climbing Terms

Gabby: A young female climber who shows great potential in climbing.
Gaston: A climbing grip using one hand with the thumb down and elbow out. The grip maintains friction against a hold by pressing outward toward the elbow.
Gendarme: A pinnacle or isolated rock tower frequently encountered along a ridge.
Geneva rappel: A modified dulfersitz rappel using the hip and downhill arm for friction, rather than the chest and shoulder, offering less complexity, but less friction and less control. 'Geneva Style' is also a description used in Australia for what is commonly referred to elsewhere as 'Australian Rappelling'.
Glacier travel: walking or climbing on a glacier; a rope is usually used to arrest falls into crevasses, but protection is not used.
Glissade: A usually voluntary act of sliding down a steep slope of snow.
Golden Retriever: When a climber is cleaning a route and forgets to pull out a piece or unclip the rope and begins to climb above the piece rendering the top rope ineffective.
Gorp: Trail mix for periodic nibbling to keep high energy level between meals on long climbs or hikes. An acronym for 'Good Ol' Raisins & Peanuts' or 'Granola, Oatmeal, Raisins, and Peanuts'.
Grade

Intended as an objective measure of the technical difficulty of a particular climb or bouldering problem. More often is highly subjective, however.
The slope of an incline. (Grade (geography))

Graunchy: A route (often off-width) requiring the use of unconventional and uncomfortable techniques.
Grigri: A belay device designed to be easy to use and safer for beginners because it is self-locking under load. Invented and manufactured by Petzl. Many experienced climbers advocate the use of an atc type device for beginners.
Gripped: Scared. Also over gripping the rock.
Gronked: Accidentally going off-route while leading and becoming lost on a rock face in an area much more difficult than the climb being attempted. The word arises from the climb "Gronk" in Avon Gorge which is notorious for this.
Grovel: To climb with obviously poor style or technique.; A climbing route judged to be without redeeming virtue.
Gumby: An inexperienced, unknowledgeable and oblivious climber; is a derogatory term. Gumbies are incapable of learning.
Gym climbing: Climbing indoors, on artificial climbing walls. This is typically for training but many people consider this a worthwhile activity in its own right.