My definition is this
What a Monster 'Cross bike is;
Drop bars
622 ETRTO
knobby tyres more (pref much more) than 35mm wide
What it isn't;
Anything with suspension
Anything with flat bars
Anything with slicks
Anything which would be better defined as a tourer, commuter, or in fact any other kind of bike.
Though as above, it needn't be too strict a definition, in fact it needn't be a definition at all really, just a type of bike which has started to gain some popularity and had no neat handle. I think Wade at Vulture is attributed with coining the term.
Lots of good pics in the Monstercross group on Flickr





