luminous(s = adj.all) aglow, lambent, lucent - softly bright or radiant; "a house aglow with lights"; "glowing embers"; "lambent tongues of flame"; "the lucent moon"; "a sky luminous with stars"
Derived forms noun luminosity₁, noun luminousness₁

1.  Shining; emitting or reflecting light; brilliant; bright; as, the is a luminous body; a luminous color. [1913 Webster]
"Fire burneth wood, making it . . . luminous." [1913 Webster]
"The mountains lift . . . their lofty and luminous heads." [1913 Webster]

2.  Illuminated; full of light; bright; as, many candles made the room luminous. [1913 Webster]
"Up the staircase moved a luminous space in the darkness." [1913 Webster]

3.  Enlightened; intelligent; also, clear; intelligible; as, a luminous mind. Brougham. [1913 Webster]

luminous, adj.
1 full of or shedding light; radiant, bright, shining.
2 phosphorescent, visible in darkness (luminous paint).
3 (esp. of a writer or a writer's work) throwing light on a subject.
4 of visible radiation (luminous intensity).

Derivative:
luminosity n. luminously adj. luminousness n.

Etymology:
ME f. OF lumineux or L luminosus

N  light, ray, beam, stream, gleam, streak, pencil, sunbeam, moonbeam, aurora, day, sunshine, light of day, light of heaven, moonlight, starlight, sunlight, daylight, broad daylight, noontide light, noontide, noonday, noonday sun, glow, glimmering, glint, play of light, flood of light, phosphorescence, lambent flame, flush, halo, glory, nimbus, aureola, spark, scintilla, facula, sparkling, emication, scintillation, flash, blaze, coruscation, fulguration, flame, lightning, levin, ignis fatuus, luster, sheen, shimmer, reflexion, reflection, gloss, tinsel, spangle, brightness, brilliancy, splendor, effulgence, refulgence, fulgor, fulgidity, dazzlement, resplendence, transplendency, luminousness, luminosity, lucidity, renitency, nitency, radiance, radiation, irradiation, illumination, actinic rays, actinism, Roentgen-ray, Xray, photography, heliography, photometer, optics, photology, photometry, dioptrics, catoptrics, chiaroscuro, clairobscur, clear obscure, breadth, light and shade, black and white, tonality, reflection, refraction, dispersion, refractivity, shining, luminous, luminiferous, lucid, lucent, luculent, lucific, luciferous, light, lightsome, bright, vivid, splendent, nitid, lustrous, shiny, beamy, scintillant, radiant, lambent, sheen, sheeny, glossy, burnished, glassy, sunny, orient, meridian, noonday, tide, cloudless, clear, unclouded, unobscured, gairish, garish, resplendent, transplendent, refulgent, effulgent, fulgid, fulgent, relucent, splendid, blazing, in a blaze, ablaze, rutilant, meteoric, phosphorescent, aglow, bright as silver, light as day, bright as day, light as noonday, bright as noonday, bright as the sun at noonday, actinic, photogenic, graphic, heliographic, heliophagous, a day for gods to stoop and men to soar, dark with excessive bright.

N  intelligibility, clearness, explicitness, lucidity, comprehensibility, perspicuity, legibility, plain speaking, precision, phonanta synetoisy, a word to the wise, intelligible, clear, clear as day, clear as noonday, lucid, perspicuous, transpicuous, luminous, transparent, easily understood, easy to understand, for the million, intelligible to the meanest capacity, popularized, plain, distinct, explicit, positive, definite, graphic, expressive, illustrative, unambiguous, unequivocal, unmistakable, unconfused, legible, recognizable, obvious, in plain terms, in plain words, in plain English, he that runs may read.

luminous energy, luminous flux, luminous flux unit, luminous intensity unit