lumen-, lumin-, lum-

(Latin: light, shine; torch, lamp; heavenly body)

luminosity (s) (noun), luminosities (pl)
1. The quality of having extraordinary mental capacity or talent: The luminosity of the character in the first act of the play as created by Ms. Scully, was astonishing, well deserving of the standing ovation which she received.
2. The energy radiated per second by a celestial body; such as, a star: John and the astronomers were using new equipment to measure the luminosity of the newly discovered star in the southern hemisphere.
3. The visual perception of the extent to which an object emits lucence: Due to the cataracts in his eyes, Mr. Smithson felt that the luminosity of his reading light had declined.
4. The fact or process of giving off brilliance; the quality of an object that produces shine: When certain botanical microscopic life in the sea are exposed to sunlight, their luminosity is increased, causing the sea to appear to shimmer.
luminosity function (s) (noun), luminosity functions (pl)
A standard measure of the responses of the eyes to monochromatic (one color) light at various wavelengths: As part of her research, the ophthalmologist, Dr. Robinson, studied the changes in the luminosity functions of the eyes of her patients.
luminous (adjective), more luminous, most luminous
1. Full of effulgence; describing the emission of visible radiation: The night sky was the most luminous Jeff had seen during his vacation, simply glittering with starlight.

Max has a watch with a luminous face which can be seen when it is dark.

2. Emitting or reflecting lucency, with or without accompanying heat: The most luminous life in the sea tends to dazzle an eerie green under the night sky.
3. Immensely bright or brightly colored: The luminous illustration in the hand-printed text drew the reader's attention to the fine designs and complimentary colors.
4. Evaluated on the basis of the visual sensation produced in an observer rather than energy measurements: Sarah gave a luminous performance of the role as Marie in the first play of the summer season.
luminous efficiency (s) (noun), luminous efficiencies (pl)
The ratio of the radiant energy sensed by the average human eye at a particular wavelength to that received: The ophthalmologist, Dr. McMahon, was requested to determine the luminous efficiency of his patient, Mr. Jones, who appeared to have difficulty perceiving particular colors.
luminous flux (s) (noun) (usually not plural)
The rate of flow of radiant energy, expressed by brightness that is emitted in a unit of solid angles by a uniform point source with intensities of one candela or the base unit of beaming intensity or the power emitted by a source of illumination: Dr. Young and the scientists measured the luminous flux using the latest equipment designed to indicate in lumen the rate or speed of light transmission.
luminously (adverb), more luminously, most luminously
A reference to, or relating to, the emission of lucidity; especially, producing self-generated radiation: Janet's face flushed luminously as if lit by an inner flame after reading the reviews in the press of her stage debut.
noctiluca (s) (noun), noctilucas (pl)
1. A plankton of large, spherical, reddish protozoa that produce glowing brightness: When present in large groups, the noctilucas make the sea appear luminous or sparkling at night.
2. Any marine animalcule that produces a phosphorescent appearance in the sea: Sailing off the west coast of the continent, Jimmy and the sailors noticed a considerable variety of noctiluca floating in the water.
3. Etymology: from New Latin Noctiluca, genus name; from Latin noctiluca, "lantern, moon"; from nocti-, "night" + lucere, "to shine".
noctilucent (adjective), more noctilucent, most noctilucent
1. A reference to bioluminescent organisms emitting light during darkness: When the black cat crossed the garden at night, it appeared as if two bright green, noctilucent balls were walking across the garden because no one could see her body but just her gleaming eyes.
2. A term used to describe high clouds that are visible at night: Standing on the hilltop at sunset, people could see the noctilucent clouds flowing eastward ahead of the wind.
oxyluminescence (s) (noun), oxyluminescences (pl)
Brilliant display of flashing lights resulting from oxidation: The oxyluminescence phenomenon takes place when certain minerals that are slowly heated to temperatures below their level of incandescence emit coruscation (sudden flashes or sparks) when in contact with oxygen or air.
pellucid (adjective), more pellucid, most pellucid
1. Transparent or clear: The lake water was remarkably pellucid so it was easy to see the old shipwreck lying at the bottom of the bay.
2. Easy to understand; clear and simple in style: Carson decided that the online dictionaries which he was using did not provide the most pellucid explanations and illustrations that he was looking for because they had a tendency to use another form of the same word being defined.
3. Permitting the passage of radiant splendor to shine through: The beautiful pellucid stained glass windows in the room cast a soft glow of light in the afternoon.
Per lumen scientiae viam invenient populi. (Latin motto)
Translation: "Through the light of knowledge the people will find a way."

Motto of Texas College, Tyler, Texas, USA.

phillumenist (s) (noun), phillumenists (pl)
Anyone who collects matchboxes and matchbooks as a hobby: As a phillumenist, Max was constantly looking for anything related to matches that are used for making fire with friction.

As a youth, Charles collected vesuvian (slow-burning matches formerly used for lighting cigars) and fusee (a friction match with a large head capable of burning in a wind) boxes and books; and then, as an adult phillumenist, he attended international trade shows with his collections.

Use of the internet has made it possible for phillumenists around the world to collaborate and to help new generations of phillumenists share a variety of lucifer-related (friction-match) items for their collections.

photoluminescence (s) (noun), photoluminescences (pl)
The emission of luminous energy from a substance as a result of the absorption of electromagnetic radiation: The frequency of the photoluminescence that is emitted is lower than that which is absorbed.

In the early evening, the sea snakes appeared to glisten in the dark as a result of the photoluminescence caused by the sun.

photoluminescent (adjective), more photoluminescent, most photoluminescent
Results of exposures to lucent or light waves that come from matter after it has absorbed photons or electric radiation: Photoluminescence is an important technique for measuring the purity and crystalline quality of semiconductors.

The rocks in the cave appeared to have a photoluminescent quality about them as they were blinking in the beam of the explorer's flashlight.

radioluminescence (s) (noun), radioluminescences (pl)
The passage of radiant energy; such as, X-rays, to a varying extent depending on the nature of the object: The radiologist, Dr. Anderson, explained to Sally that the glowing shadow seen in the radioluminescence was her healthy bone tissue.

Etymologically related "light, shine, glow" word families: ethero-; fulg-; luco-; luna, luni-; lustr-; phengo-; pheno-; phospho-; photo-; scinti-, scintill-; splendo-.