FromMiddle Englishdymnes,dymnesse, fromOld Englishdimnes,dymnys,dimness(“dimness, darkness, obscurity”), equivalent todim +‎-ness.

dimness (countable anduncountable,pluraldimnesses)

1. The state of beingdim, poorlyilluminated, almostdark.
   • 1831,Thomas Carlyle, “Symbols”, inSartor Resartus: The Life and Opinions of Herr Teufelsdröckh. […], London:Chapman and Hall, […],→OCLC, 3rd book,page155:

     So likewise a day comes when the Runic Thor, with his Eddas, must withdraw intodimness; and many an African Mumbo-Jumbo and Indian Pawpaw be utterly abolished.

• desmins,endisms,missend