Late 19th century; earliest use found in Charles Bigg (1840–1908), schoolmaster and ecclesiastical historian. From classical Latin pellūcent-, pellūcēns transmitting the passage of light, transparent, clear, apparent, use as adjective of present participle of pellūcēre, (more commonly) perlūcēre to transmit light, be transparent, to be apparent from per- + lūcēre to shine.