"A Central issue, a defining issue," is how John Major described the great European question last week. The shadow foreign secretary agreed with him: "Not a fringe issue," declared Robin Cook in his rapid-fire Cookspeak. Defining issue echoes the defining moment favoured by President Clinton, but the phrase is more to the point, because an issue does define things, which is more than can be said of a moment. It defines what people should be talking about. And about time too, you may think.

Defining the word issue itself is not so simple, as for most of its long history it has meant several things. It began as our version of the Latin exutus, itself a corruption of exitus, an exit. "No issue" could mean either that people couldn't go out that way, or - as it still does in family trees - that they had produced no children, for the word was available not only for the means or process of coming out, but also for the actual product of that coming out.

It could be a child or, later, a pamphlet; it could be a bodily discharge such as an issue of blood, or the wound through which it came. For the Elizabethans, it might be a sewer. It could be the end of something (the issue of an illness) or the result of something, the exact equivalent of the Old English outcome.

It was the lawyers who complicated matters, when the issue came to mean not just the end of the pleadings, but also the next stage - the decision as to what was in dispute - and the legal meaning was then taken up in a general way. This had happened by the 17th century, according to the Oxford English Dictionary.

A versatile word, then, and promising for puns. Think of the masthead of the magazine sold by, and in the cause of, the homeless - the Big Issue. It's a clever title.

Nicholas Bagnall