aphotic (having no light)
euphotic (of, relating to, or being the uppermost layer of a body of water that receives sufficient light for photosynthesis and the growth of green plants)
phosphene (a sensation of light caused by excitation of the retina by mechanical or electrical means rather than by light, as when the eyeballs are pressed through closed lids)
phosphorescence (persistent emission of light following exposure to and removal of incident radiation)
photic (of or relating to light)
photoactive (capable of responding to light photoelectrically)
photoautotroph (an organism capable of synthesizing its own food from inorganic substances using light as an energy source. Green plants and photosynthetic bacteria are photoautotrophs.)
photobiology (the study of the effects of light on living organisms and biological processes)
photobiotic (depending on light for life and growth)
photochemistry (the chemistry of the effects of light on chemical systems)
photocoagulation (surgical coagulation of tissue by means of intense light energy, such as a laser beam, performed to destroy abnormal tissues or to form adhesive scars, especially in ophthalmology)
photoconductivity (electrical conductivity affected by exposure to light)
photodegradable (capable of being chemically broken down by light)
photodynamic (of or relating to the energy of light)
photoelectric (of or relating to the electric effects, especially increased conductivity, caused by light)
photogram (an image produced without a camera by placing an object in contact with film or photosensitive paper and exposing it to light)
photograph (an image, especially a positive print, recorded by a camera and reproduced on a photosensitive surface)
photokinesis (movement as a response to light)
photolysis (chemical decomposition induced by light or other radiant energy)
photometer (an instrument for measuring a property of light, especially luminous intensity or flux)
photomicroscope (an instrument consisting of a microscope, camera apparatus, and light source used for making photomicrographs)
photon (a unit of retinal illumination, equal to the amount of light that reaches the retina through 1 square millimeter of pupil area from a surface having a brightness of 1 candela per square meter)
photoperiod (the duration of an organism's daily exposure to light, considered especially with regard to the effect of the exposure on growth and development)
photophilic (growing or functioning best in strong light)
photophobia (an abnormal sensitivity to or intolerance of light, especially by the eyes, as may be caused by eye inflammation, lack of pigmentation in the iris, or various diseases)
photophore (a light-producing organ found especially in marine fishes that emits light from specialized structures or derives light from symbiotic luminescent bacteria)
photopia (vision in bright light, mediated by cone cells of the retina; daylight vision)
photosensitivity (sensitivity or responsiveness to light)
photosphere (the visible outer layer of a star, especially of the sun)
photosynthesis (the process in green plants and certain other organisms by which carbohydrates are synthesized from carbon dioxide and water using light as an energy source)
phototaxis (the movement of an organism or a cell toward or away from a source of light)
phototherapy (the treatment of a disorder, especially of the skin, by exposure to light, including ultraviolet and infrared radiation)
phototonus (the state of being sensitive to or irritated by light)
phototropism (growth or movement of a sessile organism toward or away from a source of light)
photovoltaic (capable of producing a voltage when exposed to radiant energy, especially light)
Definitions are taken from:
The American Heritage® Dictionary of the English Language, Third Edition copyright © 1992 by Houghton Mifflin Company.
Electronic version licensed from InfoSoft International, Inc. All rights reserved.
Webster's Third New International Dictionary, Unabridged. Merriam-Webster, 2002.
http://unabridged.merriam-webster.com (30 Sep. 2006).
English-Word Information: Word Info about English Vocabulary (wordinfo.info).