Gigabucks is a slang term for "a lot of money." There are many synonyms for gigabucks that can convey the same idea. Some of these include: a fortune, a heap of riches, a small fortune, a substantial amount of money, a tidy sum, a windfall, boatloads of cash, stacks of money, and a whale of a lot of money. Each of these phrases offers a different degree of emphasis on the amount of money being discussed. For instance, "a windfall" suggests sudden and unexpected wealth, whereas "a small fortune" indicates a comparatively lesser sum. Regardless of the phrase used, they all indicate an impressive amount of wealth.