The British, Australian, New Zealand and South African equivalent to the American and Canadian Mom.
And all this argument about the correct way to spell it is nonsense. Why would you bother fighting about the right way to spell Mum/Mom, cheque/check or fiord/fjord? It's neither here nor there. And certainly saying it was Mum first isn't going to bring about a nation-wide reform on it's spelling in America, now, is it?