1. [n]  a descent down a nearly vertical surface by using a doubled rope that is coiled around the body and attached to some higher point
2. [v]  lower oneself with a double rope coiled aroound the body from a mountainside; "The ascent was easy--roping down the mountain would be much more difficult and dangerous"; "You have to learn how to abseil when you want to do technical climbing"

ABSEIL is a 6 letter word that starts with A.