“Macabre” is “of unknown origin”. Could “macabre” be from Arabic “maqbara” for cemetery? I don’t know Arabic, but I know Hebrew, and the root q-b-r means “grave”/“bury”. Correspondingly, “m” is not part of the root of the Arabic word; i guess it’s the prefix denoting “place” or something like this. So maybe it’s unrelated after all. I know that superficial similarity is not enough to establish relation, but still, just curious.