Freedom
It's hard to
define the word freedom. The most powerful country in the world
that started many wars claimed that they were protecting freedom. A group of people in Middle East
that plotted a lot of attacks
all over the world said they want to be free. Everyone has
a different definition of freedom. In mine, freedom is the right to be wrong, not the right to do wrong.
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Alternatives
> I can't explain why the "which" started and "which" plotted feels wrong. Technically, it's okay, but something feels off. Instead of "that", I think you can also use "who" started and "who" plotted. But "that" feels better.
> Everyone has a different definition of freedom. OR Everyone has different definitions of freedom. [I think the first one fits more with what you're trying to say].
> In mine, freedom is... => can also be "For me, freedom is..." or "In my definition, freedom is..." [I kept your original].
Overall, the corrections were just a few grammar points. What matters is that you've expressed your meaning well :). I corrected this because I liked your last sentence a lot.