The Collaborative International Dictionary of English v.0.48:

Starless \Star"less\ (st[aum]r"l[e^]s), a.
   Being without stars; having no stars visible; as, a starless
   night. --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

starless
    adj 1: not starry; having no stars or starlike objects; "dark
           starless nights" [ant: starry]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "starless":
   beamless, black, black as night, caliginous, dark, dark as night,
   dark as pitch, darkling, darksome, ebon, ebony, eclipsed,
   night-black, night-clad, night-cloaked, night-dark,
   night-enshrouded, night-filled, night-mantled, night-veiled,
   obfuscated, obscure, obscured, occulted, pitch-black, pitch-dark,
   pitchy, rayless, sunless, tenebrious, tenebrose, tenebrous,
   unilluminated, unlighted, unlit