THE TERMS "chef's knife" and "cooks' knife" are used interchangeably, an indiction of how basic this tool is to every kitchen. It's used primarily for chopping, when the knife blade rapidly and repeatedly strikes the surface of a chopping board, gradually reducing any food in its path to tiny pieces. Every part of a good cook's knife is designed to give the strong support necessary for the impact of the blade on the chopping surface.

If I could have one knife for kitchen work, this would be it.

Other knives I consider highly useful are a 3- or 4-inch paring knife, on for boning, on for slicing; a 6-inch "utlity" knife and one that has a serated blade for slicing tomatoes and bread.

Remember when selecting a chef's knife that it is employed mostly as an impact tool. Use the largest size you can hold comfortably. There is a tendency to buy a size smaller than you can really use, thus increasing the amount of work you have to do by limiting the area your blade can cover. Think in terms of an 8-inch or even a 10-inch blade.

The blade should be made of high-carbon stainless steel.

That is the only metal that can honestly be recommended for use in coastal areas or anywhere that corrosion from humid or salty air is likely to occur. It can be given a sharp edge and it will never pit or rust. Until recently, all stainless steel blades were manufactured in a way that prevented them from taking a good edge. They were so hard they were virtually impossible to sharpen once the edge was lost.

Stainless knives made in the Orient and heavily advertised here as "never needs sharpening" still have that problem. They are harder than most sharpeners and easily defeat them. But they do become dull. Avoid them.

The high carbon stainless blade you do choose should be rigid and taper evenly from bolster to tip and from spine to edge. A smooth, even curve on the broad blade surface is necessary for proper balance and will prevent food from clinging to it.

Beware of very elaborately shaped handles, ostensibly designed to fit every curve of your hand. They are less likely to fit your particular hand than a more basic shape.

Look for a full tang. The tang is the part of the blade extending into and attached to the inside of the handle. You can almost always see it sandwiched between the two halves of the handle. A full tang is the same length, width and shape as the handle. The length of the tang gives a knife good balance and supports the blade.

Choose the knife with a wide smooth bolster. The thickest part of the knife is at point where the blade meets the tang and is called the bolster.Looking down at the knife from the top you can see the thickness of the original blank of steel from which the knife was made. The thickness of the spine of the blade should continue through the bolster point into the tang. The bolster is a protective barrier between your hand and the cutting edge. Your fingers will be constantly rubbing against the bolster so it must be smooth and comfortable.

The rear part of the handle should curve downward. The handle curve is important in order to support and cushion the back of your hand against the force of impact when you bear down.

You should be able to balance a well-designed chef's knife by laying the part of the blade just below the bolster, flat across your finger.

These knives are not inexpensive. Depending on the size, the manufacteurer, and whether or not a sale is in progress, the general price range will be from $15 to $40 for a single knife. Henckles and Wusthof are dependable brands imported from Germany. The French name Sabatier, once associated with a specific factory, has been leased to more than a dozen different manfacturers there, in South America and in the Orient. There is no common quality control, but those imported by Rowoco and Cordon Blue are excellent.

Almost every manufacturer of this type of knife has a sale during the spring and again during the fall. These are the times to watch for. Prices are usually reduced by 25 percent across the entire line. Even though they are expensive, if you care for these knives properly they will truly last a life time. My set has been in use for over 20 years and it's holding up much better than I am. CAPTION: Illustration, no caption