All 3 Uses

luminous
in
Fahrenheit 451
(Edited)

They both looked quickly about the house and Montag felt his nostrils dilate and he knew that he was trying to track himself and his nose was suddenly good enough to sense the path he had made in the air of the room and the sweat of his hand hung from the doorknob, invisible, but as numerous as the jewels of a small chandelier, he was everywhere, in and on and about everything, he was a luminous cloud, a ghost that made breathing once more impossible.
p. 127.5

luminous = glowing
Out of a helicopter glided something that was not machine, not animal, not dead, not alive, glowing with a pale green luminosity.
p. 129.1

luminosity = glow (emission of light)
Montag saw the luminous dial of his waterproof [watch].
p. 147.3 *

luminous = glowing

Definitions:

(1) (luminous)
glowing or shining

(also used metaphorically to describe beauty or intelligence)
(2) (meaning too rare to warrant focus)
Much more rarely, luminous can mean beautiful, inspiring, or beautifully clear and understandable.