Dictionary of Lighting

Lighting plays a fundamental role in shaping the ambiance and functionality of any space, yet navigating the world of lighting can often feel overwhelming. From understanding different types of fixtures and bulbs to grasping the nuances of lighting design and technology, there's a lot to learn. Whether you're a homeowner looking to enhance your living environment, an interior designer aiming to create stunning visual effects, or simply someone curious about how lighting works, this comprehensive dictionary is your quick and easy guide.

In just 10 minutes, you'll be well-versed in the essential lighting terms that every savvy decorator, builder, or lighting enthusiast should know. By familiarizing yourself with these key concepts, you'll gain the confidence to make informed decisions about lighting options that best suit your needs and preferences. Whether it's choosing the right fixture, understanding light color temperatures, or optimizing energy efficiency, this dictionary equips you with the knowledge to transform any space with the power of light. So dive in, and illuminate your understanding—become a lighting expert today!

A

Accent Lighting

Lighting that focuses light on a particular area or object, such as artwork, to highlight and enhance its appearance. It's often used to create visual interest or highlight architectural features.

Ambient Lighting

Also known as general lighting, it provides overall illumination to a space, ensuring even lighting and enabling safe navigation.

ANSI

Abbreviation for the American National Standards Institute, which oversees the development of voluntary consensus standards for products, services, and systems in the United States.

Architectural Lighting

Lighting integrated into the structure of a building, often highlighting architectural features such as columns, cornices, or walls.

Art Deco

A design style popular in the 1920s and 1930s, characterized by bold geometric shapes, rich colors, and intricate detailing, often seen in lighting fixtures.

Artificial Light

Light produced by electrical sources, as opposed to natural light from the sun.

B

Backlighting

Lighting placed behind an object or surface to create a silhouette effect or to highlight the object by providing contrast.

Ballast

A device used in fluorescent and HID lighting to regulate the current and provide the necessary starting voltage.

Beam Angle

The angle at which light is emitted from a source, measured between the points where the light intensity falls to 50% of its maximum. It determines the spread of light.

Bollard

A type of outdoor lighting fixture mounted on a post, often used to illuminate pathways and driveways.

Bulb

A general term for the glass envelope that houses the light source in incandescent and fluorescent lamps.

C

Candela (cd)

The standard unit of luminous intensity in a given direction, measuring the power emitted by a light source.

Ceiling Fixture

A light fixture mounted directly to the ceiling, providing ambient or task lighting.

Chandelier

A decorative, often ornate, suspended light fixture featuring multiple arms or branches, each holding a light source.

Color Rendering Index (CRI)

A scale from 0 to 100 that measures how accurately a light source reveals the colors of objects. Higher CRI values indicate better color rendering.

Color Temperature

Measured in Kelvin (K), it describes the color appearance of light produced by a lamp. Lower values (2700K-3000K) indicate warm, yellowish light, while higher values (5000K-6500K) indicate cool, bluish light.

Compact Fluorescent Lamp (CFL)

A type of energy-efficient fluorescent lamp that is compact in size and can fit into standard light fixtures.

Cornice Lighting

A type of architectural lighting that directs light downwards from a concealed source, usually placed near the ceiling.

Cove Lighting

Indirect lighting placed in a cove, recess, or ledge at the ceiling level, directing light upwards to provide ambient illumination.

D

Daylight Harvesting

A lighting control strategy that reduces artificial lighting in response to the presence of natural daylight, saving energy and enhancing comfort.

Dimmable

A characteristic of light fixtures or bulbs that allows the light output to be adjusted or dimmed to different levels.

Diffuser

A translucent cover or panel that scatters light, reducing glare and creating a softer, more even distribution of light.

Downlight

A type of light fixture installed in or on the ceiling that directs light downwards. Often used for task lighting or to provide general illumination.

Driver

An electronic device that regulates the power to LEDs, ensuring they receive a constant current.

E

Efficacy

Measured in lumens per watt (lm/W), efficacy indicates the efficiency of a light source in converting electrical energy into visible light.

Egress Lighting

Emergency lighting that illuminates pathways, exits, and areas of egress in buildings to ensure safe evacuation during power outages or emergencies.

Emergency Lighting

Lighting that operates automatically in case of a power failure, providing illumination for safety and security purposes.

F

Fixture

The complete assembly that houses a light source, including the socket, bulb, and any other components such as reflectors, diffusers, or shades.

Floodlight

A broad-beam, high-intensity light fixture used to illuminate large areas, such as outdoor spaces or sports fields.

Fluorescent Lamp

A type of gas-discharge lamp that uses electricity to excite mercury vapor, producing ultraviolet light that causes a phosphor coating inside the lamp to glow.

Footcandle (fc)

A unit of illuminance equal to one lumen per square foot. It measures the amount of light reaching a surface.

Frosted Glass

Glass that has been treated to create a matte, diffused surface, reducing glare and providing a softer light.

G

Glare

Uncomfortable or excessive brightness caused by a direct view of a light source or its reflection. Glare can reduce visibility and cause discomfort.

Gobo

A stencil or template placed inside or in front of a light source to control the shape and direction of the emitted light. Often used in stage lighting and projections.

Grounded

Refers to electrical systems that have a safe path to the earth, reducing the risk of electrical shock.

H

Halogen Lamp

A type of incandescent lamp that uses a halogen gas to increase light output and lifespan. Halogen lamps produce a bright, white light.

Hardscape Lighting

Outdoor lighting integrated into hard surfaces such as stone walls, pathways, or steps, used for safety and decorative purposes.

HID (High-Intensity Discharge) Lamp

A type of lamp that produces light by creating an electrical arc between tungsten electrodes inside a gas-filled tube. Common types include metal halide, sodium vapor, and mercury vapor lamps.

High Bay Lighting

Lighting designed for high-ceilinged spaces, such as warehouses, factories, and gymnasiums, typically mounted 20 feet or more above the floor.

Hue

Refers to the color of light emitted by a light source, such as red, blue, or green.

I

Incandescent Lamp

A traditional type of lamp that produces light by heating a filament until it glows. These lamps are known for their warm light but are less energy-efficient than other lighting technologies.

Indirect Lighting

Lighting that reflects off walls, ceilings, or other surfaces to provide a soft, diffused illumination without direct exposure to the light source.

IP Rating (Ingress Protection)

A rating system that classifies the level of protection provided by a lighting fixture against the intrusion of dust and water. Higher IP ratings indicate better protection.

Illuminance

The measure of the amount of light falling on a surface, typically measured in footcandles or lux.

J

Junction Box

An electrical box used to connect wires and house electrical connections for light fixtures and outlets.

K

Kelvin (K)

A unit of measurement for color temperature, indicating the hue of a light source. Lower Kelvin values produce warmer, yellowish light, while higher values produce cooler, bluish light.

L

Lamp

A technical term for a light bulb, the component that produces light within a lighting fixture.

LED (Light Emitting Diode)

A semiconductor light source that emits light when an electric current passes through it. LEDs are energy-efficient, long-lasting, and available in various colors.

Lens

A transparent or translucent component used in lighting fixtures to direct, focus, or diffuse light.

Light Pollution

Unwanted or excessive artificial light that brightens the night sky, interfering with astronomical observations and disrupting ecosystems.

Lumen (lm)

A unit of measurement for the total amount of visible light emitted by a light source. Higher lumen values indicate brighter light output.

Luminaire

The complete lighting unit, including the fixture, lamp, ballast, reflector, and any other components necessary for its function.

Lux (lx)

A unit of illuminance equal to one lumen per square meter. It measures the amount of light falling on a surface.

M

Matte Finish

A non-reflective surface finish that reduces glare and provides a soft appearance.

Metal Halide Lamp

A type of HID lamp that produces bright, white light, commonly used in commercial and industrial lighting applications.

Monorail Lighting

A flexible track lighting system that allows individual fixtures to be positioned and adjusted along a single rail.

Motion Sensor

A device that detects movement and triggers a lighting fixture to turn on, commonly used for security and energy-saving purposes.

N

Natural Light

Light produced by the sun, as opposed to artificial light from electrical sources.

Neon Light

A type of gas-discharge light that produces bright, colorful light using neon gas and other noble gases.

O

Occupancy Sensor

A device that automatically turns lights on or off based on the presence or absence of people in a room, helping to save energy.

Opaque

A material that does not allow light to pass through, blocking light and creating shadows.

Outdoor Lighting

Lighting designed specifically for outdoor use, including landscape lighting, pathway lighting, and security lighting.

P

Pendant Light

A light fixture that hangs from the ceiling, typically suspended by a cord, chain, or rod. Pendants are often used for task lighting over kitchen islands, dining tables, and counters.

Photocell

A light-sensitive sensor that detects the presence of natural light and automatically turns lights on or off based on ambient light levels.

Post Light

An outdoor lighting fixture mounted on a pole or post, commonly used to illuminate driveways, pathways, and gardens.

Pot Light

Another term for recessed lighting, typically installed in ceilings to provide ambient or task lighting.

Power Factor

A measure of how effectively electrical power is used by a lighting fixture, with values closer to 1 indicating more efficient use of power.

Q

Quartz Lamp

A type of halogen lamp that uses a quartz glass envelope to contain the halogen gas, allowing for higher temperatures and brighter light output.

R

Recessed Lighting

Lighting fixtures installed into the ceiling or wall, with the light source recessed within the surface, creating a sleek, unobtrusive appearance.

Reflector

A component that directs light by reflecting it, often used in light fixtures to focus light and improve efficiency.

RGB Lighting

Refers to lighting that uses red, green, and blue LEDs to create a wide range of colors. RGB lighting is often used for decorative and accent lighting.

Rope Light

A flexible, tubular lighting fixture containing small bulbs or LEDs, used for accent lighting and decorative purposes.

S

Sconce

A wall-mounted light fixture that directs light upwards or downwards, often used for accent or task lighting in hallways, bathrooms, and living rooms.

Shade

A cover or enclosure around a light source that diffuses or directs light, reducing glare and shaping the light output.

Soft Light

Light that is diffused, creating a gentle, even illumination with minimal shadows. Soft light is often used for ambient lighting and photography.

Spotlight

A narrow-beam, high-intensity light fixture used to highlight specific objects or areas. Spotlights are commonly used in retail displays, galleries, and theaters.

String Light

A series of small bulbs or LEDs connected by a cord, often used for decorative lighting in outdoor and indoor settings.

Switch

A device that controls the flow of electricity to a lighting fixture, turning it on or off.

T

Task Lighting

Lighting designed to provide illumination for specific tasks, such as reading, cooking, or working. Task lighting is often more focused and brighter than ambient lighting.

Track Lighting

A lighting system where multiple light fixtures are mounted on a continuous track, allowing the fixtures to be adjusted and repositioned along the track.

Troffer

A rectangular or square recessed lighting fixture commonly used in commercial and office spaces, designed to fit into a dropped ceiling grid.

Tube Light

A long, cylindrical light source, such as fluorescent or LED tubes, commonly used for general or task lighting in commercial and industrial settings.

Tungsten Lamp

An incandescent lamp that uses a tungsten filament, producing a warm, yellowish light. Tungsten lamps are often used in photography and film lighting.

U

Under-cabinet Lighting

Lighting installed beneath cabinets, often in kitchens, to provide task lighting for countertops and workspaces.

Uplight

A lighting fixture that directs light upwards, often used to highlight walls, ceilings, or architectural features.

V

Valance Lighting

A type of architectural lighting installed in a valance or horizontal shield, directing light upwards and downwards for a soft, even illumination.

Voltage

A measure of electrical potential, indicating the force with which electricity flows through a circuit. Common voltage ratings for lighting include 120V (standard household voltage) and 12V (low voltage).

W

Wall Washer

A lighting fixture designed to illuminate a broad area of a wall, creating a wash of light that highlights texture, color, or architectural features.

Warm Light

Light with a color temperature below 3000K, producing a yellowish, cozy glow. Warm light is often used in residential settings to create a comfortable and inviting atmosphere.

Watt (W)

A unit of power that measures the energy consumption of a light source. Higher wattage indicates more energy consumption and, typically, more light output.

X

Xenon Lamp

A type of incandescent lamp that uses xenon gas to produce bright, white light. Xenon lamps are often used in automotive lighting and projector lamps.

Y

Yield

The amount of light produced by a lighting fixture or system, often measured in lumens. High yield indicates a brighter light output.

Z

Zonal Cavity Method

A calculation method used in lighting design to estimate the illumination provided by a fixture or system, considering factors such as room dimensions, surface reflectance, and light distribution.