It's sometimes said that the word 'jihad' in Arabic derives from a word for striving and thus doesn't mean war or holy war. Mark Liberman points out that the English word 'war' is also derived from a root that has nothing to do with war, although in this case it is confusion rather than striving. It's easy to see how either might eventually end up meaning war. (It's a little more difficult to see how the etymological root of 'war' eventually became the German word for sausage.) But both words do actually mean war.
Now, as Mark acknowledges, this doesn't stop people from using either word metaphorically to refer to something else. Muslims do use the word 'jihad' to refer to an inner, spiritual quest that involves struggling to be a good Muslim, but in fact the English word 'war' can also be used in such a metaphorical way, as can several other words that literally mean violent conflict. Some words have even more commonly come to mean nonviolent moral missions (e.g. 'crusade') and hardly ever mean war.
I have no problem if a Muslim wants to use the word 'jihad' in this way. I'd be much happier if all Muslims did no more than go through inner struggles in their personal jihad. I do have a problem if someone wants to pretend that the word never means "holy war" or especially the historically revisionist line that Muslims never meant it as war. I do have a problem if someone tries to act as if this nonviolent use of the word is standard in a way that nonviolent uses of the word 'war' are not. But even aside from the parallels between the two words, I think it's worth resisting the etymological fallacy that takes a word to mean something simply because it was derived from an archaic root that means that. The classic counterexample of 'butterfly' in English comes to mind. It doesn't have much to do with butter or flies.