A gaffer is the foreman of a stage crew. In addition, as lighting professionals know, in film and television, the gaffer is the head electrician.

But do you know what the word really means? It originated in the 16th century, when gaffer was used as an altered form of godfather or grandfather. In the 19th century, a foreman or overseer was called a gaffer, particularly in the United Kingdom, and was a master glassblower.

In September, I substituted for the vacationing William Safire and wrote an article in The New York Times Magazine about theatrical slang, particularly lighting terms.

Of course, you are familiar with all (most?) of them, but you may not know the original meanings. For example, dolly, limelight, strobe, and break a leg are commonly used by professionals as well as lay people.

A dolly, as you know, is a mobile platform, with three or four wheels, for carrying a camera, microphone, or other items. The probable origin is not a child's word for a small doll, but rather from doily, the small mat that's put under a dish or other item, like a platform. The origin of doily is from a 17th-century draper (a maker of cloth) named Doyley (or maybe Doiley).

Doll and dolly started as nicknames for Dorothy and, in the late 16th and early 17th century, took on the meaning of an attractive woman, a sweetheart, and then a polite way of referring to a mistress. William Shakespeare (1564-1616) and Ben Johnson (1572-1637) used doll in this last context.

Your major focus is the lighting field. It's fascinating that limelight, footlight, and spotlight are terms that are used by the general public in a non-lighting sense. To be in the limelight, or focus of public attention, derives from the brilliant lights that are commonly used. For youngsters or oldsters who may not remember, these lights originally containedlime (calcium oxide) heated to incandescence.

Break a leg is a delightful superstition with a Greek origin. It seems that performers in ancient Greece believed that the gods would send the opposite of a wish, so asking for a mishap would trick the gods into bringing good luck.

Let's go back to dolly. Could it be that these ubiquitous platforms were named after a woman? Lots of other words have personal derivations. An emily, for example, is slang for a broad, or floodlight, with one lamp; also called a single broad. The term probably was first used by a gaffer who had a friend named Emily.

Many luminaires are named after people or companies. The commonly used reflected light devices called fresnels are named after Augustin Jean Fresnel (1788-1827), a French physicist. He pronounced his name fray-nell, though Americans say fruh-nell.

Century lights are common in film, television, and theatre, but their origin may stump novices. It's not merely that they've been used for a century. The name refers to the original company, which no longer exists. The Century Lighting Company was taken over and its products now are made by Strand Lighting. Thousands of spotlights bearing the name Century are still used, but many people think that it's a generic name or that the company still exists. Strand also has taken over the Century stand, the three-legged, portable metal stand that holds light reflectors or other devices.

Klieg lights are used at so many premieres and other events that their name is generally known. Most people correctly pronounce them (kleeg) but often use the misspelling of Kleig. The lamp was invented by the German-American brothers John Kliegl (1869-1959) and Anton Kliegl (1872-1927).

Here are a few of my favorite terms used in film, television, theatre, and elsewhere in show business: Barndoors are hinged, rectangular flaps that obviously are akin to the doors on a farm building. Barney, the sound-deadening housing around a camera, probably has the same agricultural origin. A more colorful derivation is an old comic strip, "Barney Google," in which a racehorse named Sparkplug wore a tattered blanket. Another possibility is that the two humps on the camera magazine resembled Barney Google's eyes.

Barn words are everywhere. To barnstorm is to travel about the country, particularly to small towns, for baseball exhibitions, speeches, plays, and other performances. The word comes from the days when barns or barnlike buildings, called barn theaters, were used by barnstormers for barnstorming. In the 19th century, actors with extravagant gestures were called barnstormers. A barnyard is slang for a warehouse or other area where empty crates are stored, such as during an exhibition.

Let's get out of the barn and back to lighting. Did you ever wonder why a spotlight with a reflector back is called a birdseye? The inventor was Clarence Birdseye (1886-1956), better known for developing methods for quick-freezing foods.

A bazooka, you know, is a device on a catwalk that supports lighting units. A few readers, who are World War II veterans, know that bazookas were weapons for launching armor-piercing rockets. They were named after a comic horn popularized by comedian Bob Burns (1896-1956), who in turn named it after the slang word bazoo ("mouth" or "nose"), which is probably from bazuin, the Dutch word for "trumpet."

Whew! Perhaps you're not ready for a vocabulary quiz. Here's an easy one. A best boy is the principal or first assistant to the chief electrician. The principal assistant to the grip (stagehand) is the best boy grip. The term may have originated in the days when laborers assembled for possible work in theatres and the gaffer called, "Give me your best boy."

One of my favorites is an inky dink, also called dinky inky or simply inky or dinky. It's a small incandescent (inky) lamp. Dinky, which means small, is from the Scottish. Remember Jimmy Durante's song about inka dinka do?

Two other common names are Chromakey and Chyron. Chromakey (sometimes spelled Chroma-Key or chroma key) is an electronic process that alters the background scene without affecting the foreground. It's also called color-separation overlay (abbreviated CSO). Chryon is a major manufacturer (based in Melville, NY) of electronic image and character generators and TV graphics systems, particularly those commonly used by many TV stations and producers for lettering and graphics. The systems are so common that the company name is sometimes used generically or as a verb (to chyron an identification). "Chyron operator" sometimes appears in television credits.

My most favorite showbiz word is weenie, which is slang for a gimmick, such as a plot device or object that motivates action, perhaps a stolen treasure dangled in front of someone to tantalize, like a wiener or frankfurter. Alfred Hitchcock called it a MacGuffin, which is more enigmatic (Disney refers to highly visible, attractive structures in its theme parks as wienies, which are hot dogs).

My last name is Weiner, and I pronounce it wine-er. It's a common name in New York and Los Angeles, where some of my namesakes often call themselves ween-er. Oh well, as is said in show business, as long as you call me.

Richard Weiner, a public relations consultant at Porter Novelli in New York, is the author of Webster's New World Dictionary of Media and Communications (Macmillan).

Special offer to readers of Lighting Dimensions: Webster's New World Dictionary of Media and Communications is a 688-page collection of technical and slang terms in broadcasting, film, theatre, and related fields. An autographed copy can be obtained for only $30 (including postage) from Richard Weiner, 220 East 42nd Street, New York, NY 10017, phone: 212/601-8005.