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1. Adjective describing the gargantuan proportions and nature of an action or object. Can be used ambiguously and totally out of context

2. An exclamation of approval. Can be proceeded by "that's" or can be left alone.

pronounced MAY-ass-Stee-iff
Young Man: Did you see the size of that bodily orifice?
Jon: That's Mastif!
by The Young Man Men February 16, 2009
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