There are many things that can cause a swollen knot on a persons back. An allergic reaction to something, an insect bite, or an animal bite are things that can cause this.
It can be, its called a subdural hematoma - you might want a doctor to take a look.
The plural form of knot would be: knots
The plural form of knot would be: knots
Not really. He usually goes with the four-in-hand knot
"Typing the knot" does not mean anything (as an expression I mean). "Tying the knot" on the other hand means to get married.
A hernia
The word knot can be a noun or a verb. The noun form is a looping of rope or other material so that it cannot be untangled without passing the ends of material through the loops. The verb form means to form or tie a knot.
If a line is tangled, you most likely cannot undo it with one hand. However, if is a knot that needs to be undone, many knots can be undone with one hand. If a knot is "slipped", which means it has an end that will release it, the slipped end is pulled. This is the way you untie shoelaces, which are tied with a double slipped square knot. If the knot is not slipped, the next easy way to undo it is to "spill" the knot. Depending upon the type of knot, this usually requires two hands. To spill the knot, a section that looks like a loop is pushed or pulled in the direction away from the load which will either loosen the knot or release it. If a knot cannot be spilled or slipped, it will require 2 hands and can be difficult, sometimes also requiring a tool.
figure eight
Sounds like a swollen gland, but it could be a cyst. Best to have a doctor look at it.
There is no information listed on the processes a person can use on their tie. It is stated that there are four ways to tie a tie. Some of the ways are four in hand knot, half Windsor knot, and the traditional Windsor knot.