The Collaborative International Dictionary of English v.0.48:

Rayless \Ray"less\ (r[=a]"l[e^]s), a.
   Destitute of rays; hence, dark; not illuminated; blind; as, a
   rayless sky; rayless eyes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

rayless
    adj 1: having no parts resembling rays; not having ray flowers

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "rayless":
   ableptical, amaurotic, beamless, benighted, bereft of light, black,
   black as night, blind, caliginous, color-blind, dark,
   dark as night, dark as pitch, darkling, darksome, dim-sighted,
   ebon, ebony, eclipsed, eyeless, hemeralopic, in darkness,
   mind-blind, night-black, night-clad, night-cloaked, night-dark,
   night-enshrouded, night-filled, night-mantled, night-veiled,
   nyctalopic, obfuscated, obscure, obscured, occulted, pitch-black,
   pitch-dark, pitchy, sightless, spiritually blind, stark blind,
   starless, stone-blind, sunless, tenebrious, tenebrose, tenebrous,
   undiscerning, unenlightened, unilluminated, unlighted, unlit,
   unobserving, unperceiving, unseeing, visionless