The last works of the French impressionist painter Claude Monet...painted at his home at Giverny, show this brunescent change over time. Monet's right cataract was removed in January, 1923, and works painted after this time show a return of the blues and violets to his artistic palette
Evidently it means tending to red or brownish. But I don't find it in OneLook. Why not
a slightly more common form is brunneous; yours is spelled brunnescent, but that's only found in Really Big Dictionaries (W3).
why? 'cause it just means dark brown.
edit: I see lots of "brunescent cataracts" and "brunescent lenses" with just the undoubled "n" -- must be a strictly medical usage, and it's just like them to confuse things.
tsu: Thank you for that
"Brunneous" gives us 3 hits on OneLook, while I don't find it at all on Webster's New Explorer (330,000 entries); meaning it's very new or very obscure
At least they all agree it means dark brown
brunneous
[f. mod.L. brunneus, = med.L. brunus, f. Teut. brūn BROWN.]
Dark brown. (Chiefly in Entomology.)
1843 HUMPHREYS Brit. Moths I. 137 The hind wings are brunneous grey. 1847 Proc. Berw. Nat. Club II. No. 5. 244 Abdomen..beneath shining brunneous or ferruginous.
OED SECOND EDITION 1989