Definition of unluminous in US English:

unluminous

adjective

  • Not luminous; dim, dull.

Origin

Mid 18th century; earliest use found in John Hill (bap. 1714, d. 1775), physician and actor. From un- + luminous.

Pronunciation

unluminous

/(ˌ)ʌnˈl(j)uːmɪnəs/