slipknot

/S L IH1 P N AA0 T/
noun
  1. 1

    A knot which attaches a line to an object and tightens when pressure is applied. Also called a running knot.

  2. 2

    A knot which attaches a line to the middle of another, allowing it to slide

Source: https://en.wiktionary.org/wiki/slip%20knot, https://en.wiktionary.org/wiki/slipknot