Americans with Disabilities Act (ADA)
The American with Disabilities Act (ADA) requires owners of publically accessible areas to properly accommodate disabled persons. Under ADA, "objects protruding from walls with their leading edges between 27" and 80" above the finished floor shall protrude less than 4" into walks, halls, corridors, passageways or aisles."
Binning is the process of sorting LEDs into defined ranges of performance in terms of color, luminous flux, and forward voltage.
Color Rendering Index (CRI)
The Rendering Index is a quantitative measure of the ability of a light source to render the colors of objects compeered to a reference source. The CRI scale ranges up to 100, perfect color rendering. In most cases of lighting, the reference source is a clear sunny day, where a CRI is 100. It is recommended to use light sources as with a CRI rating as close to 100 as possible. Incandescent lamps (including many halogen lamps) have a near 100 CRI while fluorescent and LED lamps very. Note that CRI does not indicate the color temperature of the light itself and so is not sufficient by itself to specify a light source.
Correlated Color Temperature (CCT)
Correlated Color Temperature is a simple numerical expression (in degrees Kelvin) of the color appearance of a light source. Color temperature is calculated from a spectral power distribution of the source and is measured on the Kelvin scale. A low Kelvin rating (2700K to 3000K, for example) is considered "warm" in appearance. Kelvin ratings of 4000K or higher are considered" cool". While incandescent sources generally mimic a theoretically perfect "radiator", other sources such as fluorescent, HID or LED often vary from this theoretical value, so their appearance is said to be correlated to that color temperature. This means that sources with the same CCT may appear slightly different.
Candle flame, sunset/sunrise
Soft White compact fluorescent lamps
Studio lamps, photofloods, etc.
Studio "CP" light
Moonlight, xenon arc lamp
tubular fluorescent lamps or Cool White/Daylight compact fluorescent lamps (CFL)
Vertical daylight, electronic flash
LCD or CRT screen
||Clear blue poleward sky
These temperatures are merely characteristic; considerable variation may be present.
(chart courtesy of Wikipedia http://en.wikipedia.org/wiki/Color_temperature)
An exterior or interior location that is normally or periodically subject to condensation of moisture in, on, or adjacent to: electrical equipment, and includes partially protected locations.
A location not normally subject to dampness, but may include a location subject to temporary dampness, as in the case of a building under construction, provided ventilation is adequate to prevent an accumulation of moisture.
Luminous efficacy is the ration between the total light output of a light source or luminaire (lumens) and its input power (watts). Luminous efficacy is measured in lumens per watt (lm/W).
Luminaire efficiency is the percentage of the lamp lumens emitted by a luminaire. Efficiency is a reasonable way to evaluate the optical performance of a light source. The overall luminous efficacy is a measure of the efficiency of the device with the output adjusted to account spectral response curve. In other words, of the power going into a fixture, how much of the power is being used for visible light.
A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp. Lower energy cost typically offsets the higher initial cost of the lamp. The lamp fixture is more costly because it requires a ballast to regulate the current through the lamp. 
Incandescent Light Bulb
An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light that produces light with a filament wire heated to a high temperature by an electric current passing through it, until it glows. The hot filament is protected from oxidation with a glass bulb that is filled with inert gas (or evacuated). The light bulb is supplied with electrical current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections.
Incandescent bulbs are manufactured in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require line voltage that can easily be wired to existing electrical wiring within application, no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. The light quality is usually a yellow-white light emitted in all directions and varies in color temperature averaging 2600K.
Incandescent bulbs are less efficient than several other modern types of light bulbs; most incandescent bulbs convert less than 5% of the energy they use into visible light (with the remaining energy being converted into heat). 
Types of bulbs:
Decorative (D) (candle and flame shapes, teardrop and other shapes)
Reflectorized (R) (have reflective coating inside the bulb that directs the lights direction, available in a variety of beam angles; flood (FL), narrow flood (NFL), spot (SP) and narrow spot (NSP).
Incandescent – Halogen Light Bulb
Halogen light bulbs are filled with halogen gas to produce a brighter and usually whiter light than standard incandescent light sources. They burn hotter, have longer lamp life and provide more light per watt than standard incandescent bulbs. Halogen bulbs are offered in standard "line" voltage (120V) and low voltage (12V and 24V). Low voltage lamps require a transformer to step down the voltage from a higher voltage such as 120V or 270V to 12V or 24V.
Light-Emitting Diode: is a semi-conductor light source. When a light-emitting diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. An LED is often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output. 
Leadership in Energy and Environmental Design (LEED) is a rating program for buildings developed by the U.S. Green Building Council (USGBC) and increasingly worldwide. LEED is intended to provide building owners and operators a concise framework for identifying and implementing practical and measurable environmental construction, operations and maintenance solutions. Lighting and controls contribute to LEED certification in terms of Energy, Indoor Environmental Quality, and Light Pollution Reduction.
Line Voltage – 120V
Line voltage can easily be wired to existing electrical wiring within application, no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. In a U.S. residential and business application, line voltage is regulated at 120V while some commercial applications are wired at 277V.
LM-79, developed by the IES, is the approved method for testing LED luminaires for their light output (lumens), electrical power (watts), energy efficacy (lumens per watt), intensity and color.
LM-80, developed by IES, is the approved method for testing the lumen maintenance for LED boards and modules over time. LED devices must be operated and tested for at least 6,000 hours at specific temperatures. LM-80 test results do not represent life ratings for LED luminaires, but using procedures from TM-21 (see below), the data can be applied to an LED luminaire to predict useful operating life and light output over time.
Low Voltage (12 Volt and 24 Volt)
Low voltage is used in lighting to decrease the amount of volts used to operate certain types of lamps. The use of external (and sometimes internal) regulating equipment such as a transformer or driver is used to accept the line voltage coming in to decrease the output voltage to a lesser, safer amount. In the US, fixtures that use low voltage will operate at either 12V or 24V. Due to the lesser amount of volts, heat is decreased and lamp size can decrease. Low voltage is widely used in recessed lighting, linear lighting, landscape lighting and some decorative lighting.
Lumen Maintenance and LM70
Unlike conventional light sources, LEDs can operate for extremely long periods of time without failure. However, during this time, LED light output depreciates, potentially leaving an operating light source without useful light. To avoid this problem, industry consensus has defined the useful life of LED lighting products as the amount of time it takes for light output to decline to 70% of its initial value. This is called LM70 and is the method most commonly used to measure the life of LED lamps and luminaires.
Reflective Light Management. A style of lighting fixtures that use the reflective surfaces and angles to shape and direct the light source to a desired location. Popular in commercial applications however this industrial style has grown within residential applications.
Sconce (Wall Sconce)
A sconce is a type of light fixture that is affixed to a wall, using only the wall for support.
TM-21 is an IES Technical Memorandum giving guidance on how to apply LM-80 lumen depreciation data in estimating useful LED life (typically to LM70). TM-21 provides tools for extrapolating lumen depreciation, hot to correlate test temperatures to LED luminaire temperature and limits the extrapolation to size times the LM-80 test period. Under LM-80 and TM-21, an LM70 of 50,000 hours as an example must be based on a minimum of 8333 hours of test data (nearly one year).
UL (Underwriters Laboratory)
(Taken from www.ul.com)
UL is a global independent safety science company offering expertise across five key strategic businesses: Product Safety, Environment, Life & Health, Verification Services and Knowledge Services. Our breadth, established objectivity and proven history mean we are a symbol of trust and enable us to help provide peace of mind to all
UL certifies, validates, tests, inspects, audits, and advises and educates. We provide the knowledge and expertise to help navigate growing complexities across the supply chain from compliance and regulatory issues to trade challenges and market access.
It is not mandatory for lighting fixtures to have been approved by UL or have UL certification; it is up to the manufacturer or end-user to have products inspected. However, some electricians and union workers may require it for installation. To find out more, please visit www.ul.com
A location in which water or other liquid can drip, splash, or flow on or against electrical equipment.
A wet location luminaire shall be constructed to prevent the accumulation of water on live parts, electrical components, or conductors not identified for use in contact with water.
A luminaire that permits water to enter the luminaire shall be provided with a drain hole.