knot (noun) [pronounce not] – a tie (of material or people)
knot (verb) – to tie into a knot
knotty (adjective) – complicated
Here are some examples of how you can use it:
These garbage bags have drawstrings that you can tie with a knot to close them.
The cat’s hairball (= the stuff they throw up) looks like a knot of hairs and leaves.
He was so worried that his stomach tied itself into a knot.
There was a knot of paparazzi at his doorstep waiting for him to come out.
Oh, you’re thirty already. Time to tie the marriage knot!
The fisherman knotted the rope tightly.
I don’t know how to solve this. Looks like a knotty problem.