What's the adjective for darkener? Here's the word you're looking for.
Included below are past participle and present participle forms for the
verbs darken and darkle which may be used as adjectives within certain contexts.
dark
Having an absolute or (more often) relative lack of light.
Lacking progress in science or the arts; said of a time period.
With emphasis placed on the unpleasant aspects of life; said of a work of fiction, a work of nonfiction presented in narrative form or a portion of either.