>>127
Infinitesimals aren't a buzzword at all. They're an alternative approach to calculus based on the concept of defining the smallest possible number. All practiced calculus was based on them until the late 19th Century, when limits were invented and applied to make math more logically rigorous.
Although we've never been able to prove that infinitesimals are sound reasoning, there's nothing you can do with limits that you can't do with infinitesimals, and vice versa. It's like Turing machines and lambda calculus.