Here's another one, "midicomputer".
A web search yields a lot of repetitions of the unhelpful definition
(between a mainframe and a mini) and references in a couple of papers
to various systems as such (e.g. VAX 11/780 and PDP-11/40).
Did any manufacturer ever use the term to describe its own products?
...and I found this quote in an online buyers' guide:
"Instead of saying "maxicomputer", most computerists says
"mainframe", which is an old-fashioned term; but I?ll say
"maxicomputer", which is more modern and easier to understand."
Computers and hemlines...
--Chuck