fog fog /ˈfɔg/

noun

1. () Droplets of water vapor suspended in the air near the ground  ( fog )
   droplets of water vapor suspended in the air near the ground
     The dense fog obscured visibility, making it difficult to navigate.
   The dense fog obscured visibility, making it difficult to navigate.
   
2. () An atmosphere in which visibility is reduced because of a cloud of some substance  ( fogginess , murk , murkiness , fog )
   an atmosphere in which visibility is reduced because of a cloud of some substance
     The dense fog obscured visibility on the road.
   The dense fog obscured visibility on the road.
   
3. () Confusion characterized by lack of clarity  ( daze , haze , fog )
   confusion characterized by lack of clarity
   

verb

1. Make less visible or unclear  ( becloud , fog , haze over , befog , cloud , mist , obnubilate , obscure )
   make less visible or unclear
    The stars are obscured by the clouds
   The stars are obscured by the clouds
    The big elm tree obscures our view of the valley
   the big elm tree obscures our view of the valley