fog

Concise Oxford English Dictionary © 2008 Oxford University Press:
fog1

▶noun

• 1 a thick cloud of tiny water droplets suspended in the atmosphere at or near the earth's surface which obscures or restricts visibility.

  ■ Photography cloudiness obscuring the image on a developed negative or print.

• 2 a state or cause of perplexity or confusion.

▶verb (fogs, fogging, fogged)

• 1 cover or become covered with steam.

  ■ Photography make (a film, negative, or print) obscure or cloudy.

• 2 bewilder or puzzle.

• 3 treat with something, especially an insecticide, in the form of a spray.

– origin C16: perh. a back-form. from foggy.

Concise Oxford English Dictionary © 2008 Oxford University Press:
fog2

▶noun the grass which grows in a field after a crop of hay has been taken.

– origin ME: origin uncertain; perh. rel. to Norw. fogg.