abbr. compact fluorescent light

A fluorescent lightbulb in which the tube is folded or twisted into a spiral to concentrate the light output. In terms of producing light, CFLs are significantly more energy efficient than traditional incandescent lightbulbs. Because incandescent bulbs also produce a significant amount of heat, whereas CFLs do not, the total energy savings of switching to CFLs will vary based on whether and how a space is heated.