Carabiner and Holdfast

Carabiner noun - An oblong metal ring with a spring clip; used in mountaineering to attach a rope to a piton or to connect two ropes.

Holdfast and carabiner are semantically related. In some cases you can use "Holdfast" instead a noun "Carabiner".

Holdfast noun - Restraint that attaches to something or holds something in place.

Carabiner and holdfast are semantically related. Sometimes you can replace term "Carabiner" with "Holdfast", this nouns are similar.