PvM is a term you can use on Runescape and probably only Runescape. Just like PK'ing. On pretty much any other RPG game community the terms are; PvP (Player versus Player) and PvE (Player versus Environment). Now there are some silly people arguing that PvE is silly, because the environment consists of the trees, rocks and earth beneath you and around you. That is false. An environment can also consist of the living/non-living beings (i.e zombies, elementals and more) which surround you and/or have a direct influence upon you. Which is obviously what is meant when using the term PvE. If anything, you can turn the arguement 180 degrees around and argue that PvM is a far too limited term, since humanoids (Man, Black Knights, Guards, etc etc) do not classify as monsters. Runescape has in the past 10 years distanced itself from other orthodox RPG games so it is only normal to have non-orthodox ingame slang such as "PK'ing" and other, now outdated terminology such as "catching", "3-hitting" etc etc. Slang which will never see any usage outside of Runescape. Go to another game and ask, for example, if there are any "pking" or "PvM" clans and chances are, if the players haven't played Runescape, they won't understand what you mean the first time 'round.