Well, MMO is short for MMORPG, which expands to Massively Multiplayer Online Role-Playing Game; or, if you want to be especially pedantic, Massively-Multiplayer Online Role-Playing Game. The first M in MMO therefore stands for "Massively".
There's a reason for this. Back in the 1990s, the concept of multi-player games came to the fore as more and more people connected their computers together. Sometimes this was over modems (we had "modem play" for a while); sometimes it was over local area networks; sometimes it was by serial ports (daisy-chaining RS232 connections for games with more than 2 players); I even saw it done using parallel ports (normally only used for printers). However, with the new games coming out of the MUD tradition there was a step change in how many players there were. These games weren't just multi-player, they were massively multi-player. It's an adjective describing the degree to which these games were (and indeed are) multi-player.
The M in MOOC stands for "Massive". MOOC expands to Massive Open Online Course. A MOOC is characterised by the number of people taking it — tens or hundreds of thousands. The word "Massive" is entirely appropriate, as it captures the central quality of these courses — that they have a massive number of people using them. MMOs are, of course, massive in this sense — they have a lot of players. They don't have anywhere near as many players as some of the Facebook and phone games out there, though. They're also "massive" in the sense that the world they depict is often enormous; again, though, there are single-player games that are just as large if not larger.
Anyone who expands the first M in MMO to "Massive" is clearly somewhat ignorant of history. They also need to think more about why in the present the word makes sense in relative terms. There are nevertheless probably plenty of people out there who do expand the acronym the wrong way.
Professionals shouldn't, though.
Yes, I did indeed write this rant because I came across this review in the Observer's Tech Monthly games section:
