"Two Ministers quit" said the headline in the Daily Telegraph, which set me thinking about the difference between quitting, leaving and simply pushing off.

Quit somehow managed to give me a picture of Glenda Jackson walking out of Tony Blair's office with an eloquent toss of the head, as learnt at drama school, and of Tony Banks doing much the same, though perhaps with less grace. I realise quite well that the dictionaries may tell me otherwise and that leaving and quitting are the same thing after all, but dictionaries can't always be expected to convey the nuances.

This particular nuance comes mainly from the United States, which gave their own slant to the word quitter, meaning someone who does what rats do to sinking ships. I am sure there was nothing ratlike in Mr Banks's departure, and certainly not in Miss Jackson's, since there were rumours that she would really rather have stayed. I am only suggesting that quit, nice and crisp as it is, was not exactly the mot juste here.

Noah Webster had a note about quit in the first edition of his American Dictionary of the English Language, published in 1828. "The sense of quit," he said, "is to leave, or withdraw from ... It does not necessarily include the idea of abandoning, without a qualifying word. A man quits his house for an hour, or for a month. He quits his employment with the intention of resuming it." This was a suggestive point of old Noah's. If he felt he had to insist that quit could sometimes simply mean "leave", it must have been because for a very great many Americans it did not mean "leave", but something much more loaded. Webster was doing his bit to maintain what he saw as the "purity of the language" just as Dr Johnson had hoped to do 70 years earlier, though with no more success than Johnson had.

Of course the word could imply a range of things in Johnson's time, as it does now, but in America the sense it conveys of leaving off something, of washing one's hands of it, is one of the strongest, and it's becoming stronger here too. In Britain we stop smoking, or try to; in the States they quit it. They say "Quit fooling". If Microsoft's Encarta World English Dictionary catches on, the American way of talking might well conquer entirely. I'm sorry it has to be Microsoft because Bill Gates is rich enough already, but apart from that I can't say the prospect worries me too much.

Kathy Rooney, the new dictionary's supremo, made a silly remark last week. British English dictionaries, she is reported to have said, were perpetuating a view of the language that was "imperialist and supremacist". Supremacist? Haven't we been borrowing from the Americans for about 100 years, and been happy to do it? The words boss (meaning manager), lobby (the verb), caption (under a picture), joy-ride, sidetrack, rowdy and the expression Indian summer, to name but a few among many, all originated in North America, and were being used here before the First World War. Ms Rooney is kicking at an open door.