IPA: /ˈæbsaɪlər/
KK: /ˈæbsaɪlər/
A person who descends a steep surface, such as a rock face or building, using a rope.
The experienced abseiler descended the cliff with ease.
Abseiler is formed from "abseil" (from German "abseilen", meaning to rope down) and "-er" (meaning a person who). An abseiler is a person who descends a rope, typically in climbing or rescue situations.
Imagine someone 'roping down' ('abseil') from a height — the '-er' indicates that this person is doing the action. That's how you remember that an abseiler is someone who descends using a rope.