Something that contributes to producing a result: ingredient.

In Latin *factor* means simply “doer.” So in English a factor is an “actor” or element or ingredient in some situation or quantity. Charm can be a factor in someone's success, and lack of exercise can be a factor in producing a poor physique. In math we use *factor* to mean a number that can be multiplied or divided to produce a given number (for example, 5 and 8 are factors of 40). And in biology a gene may be called a factor, since genes are ingredients in the total organism.

A person whose job involves doing many different kinds of work.

This odd word doesn't come from ancient Latin, but it was coined to look as if it did. The term *Johannes factotum*, meaning “Jack-of-all-trades,” first shows up in writing in 1592 to describe none other than Shakespeare himself. The word *gofer* is similar to *factotum* but a bit less dignified. In other words, a factotum is an assistant, but one who may have taken over some fairly important functions.

(1) Easily accomplished. (2) Shallow, superficial.

A facile suggestion doesn't deal with the issue in any depth, and a facile solution may be only temporarily effective. A facile writer is one who seems to write too quickly and easily, and a careful reader may discover that the writer hasn't really said very much.

To make (something) easier; to make (something) run more smoothly.

Facilitating is about getting things done. Clever employees are quietly facilitating all kinds of useful activity within their organizations all the time. People who lead therapy groups or workshops are often called *facilitators*, since their job isn't to teach or to order but rather to make the meetings as productive as possible. Even businesses now use facilitators in meetings where they don't want any person's particular desires to outweigh anyone else's. The *facilitation* of a rewarding discussion should be a facilitator's only goal. Today, in recognition of the many different situations that may call for a facilitator, there is even an International Association of Facilitators.

In physics, the standard unit for measuring the rate of the flow of light.

There are two common units for measuring light, the candela and the lumen. Both are recognized as standard international units, which also include the second (for time), the kilogram (for weight), and the meter (for length). The *candela* is a measure of intensity; an ordinary candle gives offlight with the intensity of about one candela. The lumen is a measure of “luminous flux” ; a standard 100-watt lightbulb gives off 1500–1700 lumens. Luminous flux indicates how much light is actually perceived by the human eye. Technologies vary in how efficiently they turn electricity into light; halogen lights produce about 12 lumens per watt, ordinary incandescent lightbulbs produce about 15 lumens per watt, and compact fluorescent bulbs produce about 50 lumens per watt.

(1) Producing or seeming to produce light. (2) Filled with light.

*Luminous*, like its synonyms *radiant, shining, glowing,* and *lustrous*, is generally a positive adjective, especially when it describes something that doesn't literally glow, such as a face, a performance, or a poem. Luminous signs depend on a gas such as neon, krypton, argon, xenon, or radon—and you can use luminous (DayGlo) paint to make your own signs. New technologies have now given us luminous fabrics, which are being used to produce striking or creepy effects in clothing, upholstery, and interior surfaces.

Relating to light given off by living organisms.

*Bio-* comes from the Greek word for “life”. On land, fireflies, glowworms, and the fox-fire fungus are all known for their *bioluminescence*. In the sea, bioluminescent life-forms include plankton, squid, and comb jellies, as well as some unusual fish. Most deep-sea animals are bioluminescent, but single-celled algae living at or near the surface can also create a remarkable show, as they often do in Bioluminescent Bay on the Puerto Rican island of Vieques. But bioluminescence is unknown in true plants, and mammals, birds, reptiles, and amphibians never got the knack of it either.

A very famous or distinguished person.

The Latin word *luminaria* could mean either “lamps” or “heavenly bodies.” For medieval astrologers, the luminaries were the sun and the moon, the brightest objects in the heavens. Today a luminary is usually a person of “brilliant” achievement: a celebrity, a “leading light,” or a “star.”