duskening

Verb

dusken (third-person singular simple present duskens, present participle duskening, simple past and past participle duskened)

1. (transitive) To make dusky or obscure.
   • It was last seen and heard of by some macgillic-cuddies above a lonely valley of their reeks, duskening the greylight as it flew, its cry echechohoing among the anfractuosities: pour la dernière fois,' The blackbulled ones, stampeding, drew in their horns, all appailed and much upset, which...1932, James Joyce, “From a Banned Writer to a Banned Singer”, in The Complete Works of James Joyce, published 2016
2. (intransitive) To grow or become dusky.
   • Noble you must be: noble too am I / If true the tale that Danewulf loves to tell / When twilight duskens round the crackling logs1801, Henry James Pye, Alfred