Ha, its not AT ALL related! “Mujahideen” comes from the term “jihad” which means exerting effort (and can refer to the mainstream understanding of making effort to fight in war, or the more general Arabic meaning of exerting effort in anything else; i think Muhammad once said that the hardest jihad is that which we exert against our own selves, our own whims, desires, etc).
Mujadila comes from the noun jidal, or argument.
The trick in Arabic is that the way words are formed is v similar depending on what the word “does”. So almost any term referring to a person DOING something “looks” the same. “Mu-xxx”. So the person who is a believer is called Mu’min; a believer in islam is called Muslim. Person who reads Quran can be Qari’ or Muqri’… The person who says fatwa is called Mufti – u see?
So the only thing in Arabic common between mujadila and mujahid (a single of mujahideen) is the letter “j”. The “mu” is default and the rest of the word totally unrelated 🙂 ok, i see there is also a “d” but really… It’s like the similarity between the words “bike” and “bake”, you know?