What's a Milf

I read today that the BBC's over-paid Jonathon Ross has been cleared by a committee of his own BBC bosses for calling Nigella Lawson a 'Milf' on his show. What can this mean. My spellchecker doesn't recognise it. 'Member of the Institute of Low-fat Food perhaps. He was cleared of saying a few other things as well, which I could understand all too well - language I thought more appropriate to a porn channel. What really struck me though was the reason that this committee gave when proclaiming the 'not guilty' verdict. It seems that seriously foul language is ok because Jonathon Ross "has a well established reputation for robust humour and language". What can Lord Reith be thinking?

Perhaps the BBC, now that she has decided to send all of her staff on 'honesty courses' will ask that an additional module be slipped in on 'appropriate language'. But this brings me back to the word 'Milf'. Its a word with a rather nice ring to it. Don't think I'll use it in a public speech until I know exactly what it means.