Middle English flaschen, of imitative origin
- 1: rush, dash —used of flowing water
- 2: to break forth in or like a sudden flame or flare
- 3:a : to appear suddenly <an idea flashes into her mind>
- b : to move with great speed <the days flash by>
- 5:a : to give off light suddenly or in transient bursts
- 6: to change suddenly or violently into vapor <hot water flashing to steam under reduced pressure>
- 7: to expose one's breasts or genitals usually suddenly and briefly in public
- 8: to have sudden insight —often used with on
A flash is a device used in photography producing a flash of artificial light (typically 1/1000 to 1/200 of a second) at a color temperature of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the electronic flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs and flammable powders. Modern cameras often activate flash units automatically.
Flash units are commonly built directly into a camera. Some cameras allow separate flash units to be mounted via a standardized "accessory mount" bracket (a hot shoe). In professional studio equipment, flashes may be large, standalone units, or studio strobes, powered by special battery packs or connected to mains power. They are either synchronized with the camera using a flash synchronization cable or radio signal, or are light-triggered, meaning that only one flash unit needs to be synchronized with the camera, and in turn triggers the other units, called slaves.
The Adjusters are the eternal ancestors, the divine originals, of your evolving immortal souls; they are the unceasing urge that leads man to attempt the mastery of the material and present existence in the light of the spiritual and future career. The Monitors are the prisoners of undying hope, the founts of everlasting progression. And how they do enjoy communicating with their subjects in more or less direct channels! How they rejoice when they can dispense with symbols and other methods of indirection and flash their messages straight to the intellects of their human partners! (108:6.7)