To "diffuse" something means to "spread it out". Therefore, to say that someone's "legs ache diffusely" would mean that the pain is spread out through her legs, rather than only in one area. "Diffusely" would be another way of saying "all over".
That would be bipedalism.
I am not sure what you mean but animal which walk on their hind legs have straight legs and they are called bipedalanimals.
The Seven Year Ache is a term related to the feeling or desire to find a romantic fling despite being in a long-term committed relationship such as marriage.
A small seat that has three legs as opposed to four (or more)
It normally is a term used if a person has athletic or fit looking legs
Stomach ache translates as Bauchschmerzen, Bauchweh, or Magenscherzen
The name Crookshanks seems to refer to the cat's bandy legs, from crook, meaning "a bend", and shank, a term for the lower part of the legs. Hope this was helpful :)
Earache is the common term for pain in the ear.
It means you stand with your feet pointing in opposite directions, legs open from the hip-socket.
A continuous or prolonged dull pain in some part of one's body is called an ache. An ache is a uncomfortable feeling that you can handle can be relieved with painkillers. It doesn't interfere with your daily activities or sleep. Pain is an unbearable feeling that can cause you to be unproductive during this period, it can also be relieved with painkillers but takes time to subside.
One word when you are refering to the term, I have a HEADACHE.
The slang term "Shanks Pony" Means To Walk There. Your shanks are the parts of your legs between your knees and your ankles.