It's a Georgian word too (მაგარი) adjective meaning hard or strong... when used with the -ა ending (it is) -- მაგარია -- it means something like "great!" (Not completely positive about this. Will need to hit up Georgian friends to hammer it down.)
Not one of my favourite Italian words, mainly because it's almost impossible to decipher. It's also one of the kind of words that when used by a foreigner is invariably out of context. Italians will then tell you that you didn't roll your shoulders correctly or that you have the wrong style of facial hair.
Hard to translate because of its various meanings. It can mean perhaps, as well as yeah, right, and so on. But when used alone, e.g. answering a question, it gets an aftertaste of impossibility: ...If only it were possible.