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"Islam" and "muslim" are alternative anglicizations of the arabic "'aslama", meaning, "one who submits to God". Arabic is in the same language family as Hebrew and has roots that contain similar meanings. "Salam", for example, is typically how they would say peace, and they like to say that they are a religion of "peace". However, just like in Hebrew, this concept of peace is not the fundamental meaning of the root. It is, largely the same as in Hebrew, except that we also have the idea of submission and surrender attached to the idea. (Maybe it is there in Hebrew too, but I have only come across it in description of the Arabic root.) If applied personally, this could be a very peaceful idea indeed, but I think there's plenty of indication that many intend to bring this kind of "peace" to others, which makes "peace" a bit more ominous.