noun. That's a lot of zeroes, man.
Related terms: bazillion, gazillion, flazillion, quatrillion, katrillion, bagillion, bajillion, kajillion, mazillion, zazillion, fafillion, kazillion, fuckillion, frigillion, shizillion, shazillion, crapillion.
Real citation: "Everything Spielberg looks at sideways and backways makes a buttillion dollars anymore (yes, that's a lot of dollars)."
(March 6, 2002, http://www.chatterwaul.com/odd/archives/0302.php?id=572&cmt=1)
Made-up citation: "Generally speaking, an assman has a buttillion reasons to love the heinies of the bootylicious."