Does anyone an alternative name for step-up and step-down filters?

I’m looking into buying a couple of new lenses for my DSLR kit, and I’m aware that the most common filter sizes range from 52mm-77mm. But instead of buying filters for each size there is, I remember reading somewhere, that I should just get them all in 77mm, and buy step…-down (?) filters…Is it advisable for me to do this?? =S They say that vignetting would only occur if I were buy smaller filters and stick them on lenses with larger filter threads, but…there’s something about having to only buy one filter, to save a crapload of money that seems too good to be true…