luco-, luc-, luci-, lux, -lucence, -lucent

(Latin: light, lights, shine, shines, shining)

1. A reference to bioluminescent organisms that emit radiance during darkness.
2. Shining by night; as with a noctilucent cloud, a cloud of a kind that occasionally is seen at night in the summer in high latitudes, which occurs in the mesopause (atmosphere) and which some authorities believe is composed purely of cosmic dust and others of ice condensed around cosmic dust particles.
3. Designating or of a luminous cloud of unknown composition, visible at night in the polar regions at an altitude of around 50 miles.
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.
The light-giving substance in phosphorescent animalcules.
Shining at night, phosphorescent.
A genus of bioluminescent marine organisms that, when grouped in large numbers, make the seas phosphorescent.
opaque, translucent, transparent
opaque (oh PAYK) (adjective)
1. Difficult to understand: Manfred's oral instructions were opaque and Dennis had to ask for an explanation.
2. Regarding something which does not allow light to pass through: The windows were painted black so they would be opaque, thus permitting the photographer to work in his photo-processing laboratory without unwanted illumination.
translucent (trans LOO suhnt, tranz LOO suhnt) (adjective)
Pertaining to something which is not completely clear or transparent, but clear enough to allow light to pass through: The frosted glass in the door was translucent.
transparent (trans PAIR uhnt, trans PAHR uhnt) (adjective)
1. Concerning light being able to pass through: The new window in the sunroom was transparent and let in all the sunshine.
2. Characteristic of something self-evident; obvious; apparent: Trina's facial expression was so transparent that Susan always knew what she was thinking.

The information from the lecture was completely opaque to Ryan and so he couldn't understand a thing.

After Howard read the text book, his mind felt more translucent, as if some light on the subject was getting through and the information was beginning to make sense, but not completely.

Then, after Marla asked for an explanation, the answer suddenly became transparent.

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.
Transparent to X-rays.
1. Reflecting light; bright.
2. Casting back light; shining, gleaming, bright, refulgent.
roentgenolucent (adjective), more roentgenolucent, most roentgenolucent
A reference to materials that allow X-rays to penetrate with a minimum of absorption: The representative areas of the roentgenolucent film appear to be dark on the radiograph.
Sic luceat lux vestra.
May your light thus shine.

Motto of Buxton College, U.K.

Sit lux.
Let there be light.

Motto of Tarkio College, Missouri, USA.

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