flasher

The term "flasher" is most widely known as a noun for a person who exposes themself in public, especially to shock, upset, or alarm other people. This is usually understood as indecent exposure and is treated as a criminal act in many places. In normal conversation, this is often the first meaning people think of, and it carries a strongly negative sense.

Outside that meaning, "flasher" also has several practical uses. In the automotive world, it can mean the relay or unit that makes a vehicle's turn signals blink. In general equipment use, it may refer to a device or warning light that flashes on and off. In fishing, a "flasher" is a shiny lure or attractor, often made of metal or plastic, used to reflect light and draw fish toward the line.

In technology, the related verb "to flash" can mean writing firmware or software onto a device, and a "flasher" may be the tool or program used to do that. So the word can refer either to a person, usually in a negative social sense, or to a thing that flashes, makes something flash, or is used in a flashing-related process. The exact meaning depends heavily on context.