figure 9

Short definition from Wiktionary

Noun

1. 1
   A technical climbing technique used in ice climbing to gain a respite and lessen slack and distance from the undersurface/ceiling which one is climbing underneath, which appears like a number "9" in shape, with one arm anchoring the climber to the surface while hanging upside-down, and one leg wrapped around that arm, forming a figurative "9" in shape.