radiolucence (rā´dēōloo´sens),

n relative term indicating the comparatively low attenuation of a radiographic beam produced by materials of relatively low atomic number. The image on a radiograph of such materials is relatively dark because of the greater amount of radiation that penetrates to reach the film.
References in classic literature ?
The scatterbrain that gave La Mancha more Rich spoils than Jason's; who a point so keen Had to his wit, and happier far had been If his wit's weathercock a blunter bore; The arm renowned far as Gaeta's shore, Cathay, and all the lands that lie between; The muse discreet and terrible in mien As ever wrote on brass in days of yore; He who surpassed the Amadises all, And who as naught the Galaors accounted, Supported by his love and gallantry: Who made the Belianises sing small, And sought renown on Rocinante mounted; Here, underneath this cold stone, doth he lie.
Radiograph in dogs with nasal aspergillosis may show generalized radiolucence of nasal cavity secondary to turbinate tissue destruction.