Knotting

[Renato]

The action or craft of tying knots in yarn to make carpets or other decorative items.

[Couch Potatoe]

When animals mate, specifically canines--Im actually not sure about felines--the penis enlarges during climax and remains enlarged to the point where he is literally stuck inside the female for as long as it the mating process goes on.
This happens to ensure [insemination], and the male can ejaculate several times before he is shrinks down small enough to unmount. This is used as [a kink] of sorts in hybrid / [abo] fanfictions.

[Jessica]

Just before a dog cums the [centre] of its [penile shaft] expands out. So the cum doesnt [leak out].

[Vania]

present participle of knot