Noun
alpine butterfly knot (plural alpine butterfly knots)
A type of knot used to provide an anchor point on a long line. Much used by mountaineers. Also known simply as the butterfly knot.
Basic useful knots * Alpine butterfly knot for a secure loop in the middle of a rope when the ends aren't free * Bowline for tying a loop in the end of a rope, as around one's waist or to secure a ring or grommet. Source: Internet