Verb overcloud has 2 senses
  1. overcloud, cloud over, cloud up - become covered with clouds; "The sky clouded over"
    --1 is one way to darken
    Sample sentences:
    Something ----s
    It is ----ing
  2. obscure, bedim, overcloud - make obscure or unclear; "The distinction was obscured"
    --2 is one way to change, alter, modify
    Sample sentences:
    Somebody ----s something
    Something ----s something
,
TOP