While there are hundreds of terms used in lighting, the ones listed below are some basic ones used in conjunction with most lighting requirements.
Watts - Bulb wattage is a measure of electrical power, not necessarily the amount of light produced. Wattage describes the amount of power going in, not coming out.
Lumens - A unit of luminous flux; overall light output; quantity of light, expressed in lumens. For example, a dinner candle provides about 12 lumens and a 60-watt soft white incandescent lamp provides about 840 lumens.
Initial Lumens - The measure of the amount of light a lamp produces after it has been operating 100 hours.
Lumens-Per-Watt-ratio - The LPW value is similar in some ways to miles-per-gallon rating for a car, since it expresses what you can get out of a lamp in terms of what is put into it.
Foot-Candle (fc) - The foot candle is a measure of the quantity of light which falls onto a surface. Thus, the lighting level of a room is usually described as a certain foot candle level.
Candelas or Candlepower - The unit of measure indicating the luminous intensity (candlepower) of a light source in a specific direction; any given light source will have many different intensities, depending upon the direction considered. It is a measure of the light source itself.