Stands for An Awkward Rush and Mission Savers (I know it makes no sense- the thing was on a Japanese game called Wild Arms). ARMS are weapons like a gun or some other technological advance that only certain people (in Wild Arms, only Rudy and Calamity Jane could use them as far as the player was concerned). These ARMS are the remnants of a lost civilization, but certain armssmiths can work on them and upgrade them. Though, where they get their business is anyone's guess...

Also, since playing Wild Arms 2, I find that it is also the name of the group founded by Irving to protect the world. Apparently, it means something else in the English version, but I can't remember what it said. If I remember, I will be sure to put it here.