February 1, 1989

LEAD: David Shulman just received a most welcome letter. The editor of the Oxford English Dictionary wrote to say the next supplement to the prestigious lexicon would list Big Apple as a synonym for New York City. Heretofore, Big Apple has been listed only as a dance.

LEAD: CATFISH is the Cinderella of seafood, transformed by scientists from a bewhiskered, muddy-tasting, bottom-feeding wild creature into a cultured and cultivated delicacy. Only a few years ago the channel catfish was recognized as a good candidate for farming. Now consumers, chefs and nutritionists are finding the mild white flesh of farm-raised channel catfish tasty and healthful.

LEAD: FOR most people, walking is a simple matter of putting one foot in front of the other. In the cosmic scheme of things, it is up there with sleeping and sitting, something we take for granted, as life shambles along. But there is a new movement afoot.

LEAD: No snow here, so the city is postponing the winter festival that every year but this year turns downtown State Street into a ski run.

LEAD: By raising interest rates substantially in the last 10 months, the Federal Reserve helped extend the nation's long economic expansion, Alan Greenspan, the Fed's chairman, said today.