There’s a rude gesture in Pickwick that I don’t quite understand. Mr Jackson, a young lawyer’s clerk in conversation with Mr Pickwick, ‘applying his left thumb to the tip of his nose, worked a visionary coffee-mill with his right hand, thereby performing a very graceful piece of pantomime (then much in vogue, but now, unhappily, almost obsolete) which was familiarly denominated “taking a grinder”’. When I asked my husband he said, ‘Something sexual’, which I think unlikely.

I’d contemplated grinding while trying to find out whether coffee grounds are so called because they are ground-up coffee or because they are like earthy ground fallen to the bottom of the cup. There is an old joke: ‘Waiter, this coffee tastes like mud.’ ‘Well, sir, it was only ground this morning.’ I was surprised to find that the evidence is for coffee grounds taking their name from earthy ground; Thomas Macaulay mentioned grounds in a teacup, and tea isn’t ground.

Ground, the past of grind, and ground, the earth beneath our feet, are unrelated in origin. The earthy ground has produced dozens of meanings, with German mystics making God the ground of our being. Even less clear is the phrase ground rules, now much in vogue.

Certainly ground rules, like house rules, are those that apply in a particular place. The origin is in 19th-century baseball. (Parenthetically, with regard to the current controversy over batter as a name for batsmen in cricket, these were called strikers in New Articles of the Game of Cricket, 1775.)

But if you rummage through newspaper references to ground rules it is often impossible to tell whether the connotation is ‘house rules’ or ‘fundamental rules’. My husband’s eye was naturally caught by a woman in the Sunday Telegraphtalking about ground rules: ‘I couldn’t do with a man who lounged on the couch and drank beer.’ But when the Senate laid down ‘ground rules around today’s debate on the deal to extend the debt limit’, were they house rules or fundamental rules?

Often, as with the clichéd use of Shakespeare’s sea change, it makes no difference if one simply omits the adjective. A change is a change and a rule a rule.