Q From Richard Bolingbroke: Please can you tell me what mullered means and how old it is. I have only heard it in the last few months. Some people use it in engineering to mean damaged, but it seems to mean drunk too.
A This British slang term came to wide public notice in the early 1990s, though it has certainly been around for much longer in the spoken language. Jonathon Green, in his Chambers Dictionary of Slang, suggests that one sense, to be badly beaten up, has been in UK prison slang since the 1950s.
In modern usage it has the two senses you give. When it refers to objects, it doesn’t so much mean simply broken as extensively damaged or even totally destroyed (“At the end of a massive traffic queue there was a gorgeous Ferrari that had been absolutely mullered. Mullered I say. One side of the car had completely disappeared and one of the wheels was about 200 yards down the road.” — in a BBC sports blog, 12 June 2008).
In sports it has a somewhat less catastrophic sense of being badly beaten, outclassed or outplayed by the other team (“Predictably, the scrum was mullered, the ball turned over and a Quins try was the result.” — in the Irish Independent, 20 October 2008).
My impression is that the drunkenness sense is less common in print, though it’s well known, especially in Scotland and the north of England (“Ok, so we can’t afford her clothes, her lifestyle or get mullered and still look fresh as a daisy the next day.” — Daily Record, Glasgow, 13 September 2008).
Where it comes from is disputed. Jonathon Green suggests it’s a variant form of an older regional verb mull, to grind to powder, pulverise or crumble. He also notes that an alternative spelling is mullahed, suggesting some vaguely perceived Islamic connection, which the Oxford English Dictionary argues is a folk etymology.
In its recent revision of the term, the OED’s editors argue for a separate origin for the drunkenness sense from that of being beaten or destroyed. They agree the former is probably from the verb mull; they suggest it may be tied in with mulled for a hot spicy drink, where the link could be with the grinding of the spices. However, they suggest that the latter sense is from the British dialect of the gypsy language Romani, in which there is a stem mul-, derived from the verb “to die” (which, by the way, can be traced directly back to the Sanskrit origins of the Romani language).
As matters stand, this is the best we can do.