What is the meaning of the word "knot"?

Definitions:

a hard cross-grained round piece of wood in a board where a branch emerged noun
- the saw buckled when it hit a knot
a tight cluster of people or things noun
- A small knot of parishioners listened to the sermon.
any of various fastenings formed by looping and tying a rope or cord upon itself or to another rope or to another object noun
- They made a sturdy knot while tying up the boat.
make into knots verb
- make knots out of
something twisted and tight and swollen noun
- their muscles stood out in knots
tie or fasten into a knot verb
- knot the shoelaces