1 a : a part that forms when you tie a piece of rope, string, fabric, etc., to itself or to something else
She tied the rope in a knot.
He made/tied a knot in the rope.
untie a knot
loosen/tighten a knot
1 b : a part where something has become twisted or wrapped around itself
The electrical cord was tangled in knots.
She tried to untangle the knots [=tangles] in the child's hair.
— often used figuratively
The project has been tied up in political and legal knots for years. [=nothing has happened with the project for years because of political and legal problems]
2 : a painful or uncomfortable feeling of tightness in part of your body
a knot in a muscle
massaging the knots out of my back
I was so nervous that my stomach was in knots. [=I had an unpleasant and tight feeling in my stomach]
3 : a dark round mark on a piece of wood that shows where a branch grew
a board full of knots
4 : a way of arranging long hair by twisting it into a round shape at the sides or back of the head
She pulled her hair into a knot [=bun] at the back of her neck.
5 : a group of people who are standing or sitting close together
A knot [=cluster] of people blocked the door.
6 : a unit of speed equal to one nautical mile per hour
Wind is from the north at 12 knots.
sailing at six knots