THE EXPRESSION video nasty has not yet reached the statute book, but it has got well beyond being just a headline tag, and can be found, though sometimes in inverted commas, in the news columns of respectable dailies. This is rather odd, because nasty used to be a feeble word, first-class for a passing insult ('You've got a nasty mind') but without much bite. No one 50 years ago would have thought it adequate for the films whose bad influence on the young has been troubling MPs.

Children enjoyed using the word, particularly about food such as tapioca or bread-and-butter pudding. Some of them could recite with glee the rhyme they had learned from their grandparents:

'Mama, what is that nasty mess that looks like strawberry jam?'

'Hush, darlings, that is dear papa, run over by a tram.'

In short, nasty was a nursery word. It wasn't much helped by Stella Gibbons's satirical Cold Comfort Farm, in which seeing 'something n-a-a-a-sty in the woodshed' had unbalanced one of the Starkadders for life. However obscene the nameless thing, it was hard to take nasty too seriously after that.

Until the 1980s video nasties were called 'horror videos'. Horror had a long and useful record. Why the change? The word had certainly been overused by the tabloids; but I think it was really because by then horror had come increasingly to be reserved for films about Count Dracula, Frankenstein's monster and so on, which, compared with more recent material, were mere fairy-tales. Retailers might still put it all under Horror, but for the real sewage another word was needed.

The choice of nasty may have originated in the United States, where it is a stronger word than it has been here. Anyway, it has come back into its own and, in its new context, stinks just as powerfully as it did in its early days, when it implied actual filth of the smelliest sort; by the 17th century it also meant morally repulsive. We certainly need it now.