All 4 Uses of

luminous
in
The Fall of the House of Usher

A cadaverousness of complexion; an eye large, liquid, and luminous beyond comparison; lips somewhat thin and very pallid, but of a surpassingly beautiful curve; a nose of a delicate Hebrew model, but with a breadth of nostril unusual in similar formations; a finely moulded chin, speaking, in its want of prominence, of a want of moral energy; hair of a more than web-like softness and tenuity; these features, with an inordinate expansion above the regions of the temple, made up altogether a countenance not easily to be forgotten.†

Wanderers in that happy valley Through two luminous windows saw Spirits moving musically To a lute's well-tuned law, Round about a throne, where sitting (Porphyrogene!)†

The pallor of his countenance had assumed, if possible, a more ghastly hue—but the luminousness of his eye had utterly gone out.†

But the under surfaces of the huge masses of agitated vapor, as well as all terrestrial objects immediately around us, were glowing in the unnatural light of a faintly luminous and distinctly visible gaseous exhalation which hung about and enshrouded the mansion.†
*

Definitions:

(1) (luminous)
glowing or shining

(also used metaphorically to describe beauty or intelligence)
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much more rarely, luminous can mean beautiful, inspiring, or beautifully clear and understandable.