Source : Webster's Revised Unabridged Dictionary (1913)

Infuscate \In*fus"cate\, v. t. [L. infuscatus, p. p. of
   infuscare; pref. in- in + fuscare to make dark, fr. fuscus
   dark.]
   To darken; to make black; to obscure.

Source : WordNet®

infuscate
     v : darken with a brownish tinge, as of insect wings