blur
I
 /ˈblɚ/  noun  ,  pl   blurs
  1 [  count  ] : something that you cannot see clearly
  — usually singular
   He passed by in a blur of motion.
   As the train sped on, everything outside the window was a blur.
   I looked out at the blur of faces in the audience.
   The letters are just a blur without my glasses.
  2 [  singular  ] : something that is difficult to remember
   The whole weekend is just a blur to me. [=I don't remember the events of the weekend very clearly]
  blur·ry /ˈblɚri/  adj  , blur·ri·er, -est [or more ~; most ~]
   a blurry image
   She's suffering from blurry vision.
   The letters are blurry [=blurred] without my glasses.
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II
  verb  , blurs, blurred, blur·ring
  1 [  + obj  ] : to make (something) unclear or difficult to see or remember
   a technique that blurs the edges of the image [=makes the edges of the image less sharp]
   The tears in my eyes blurred the words on the page.
   His novel is based on historical occurrences but it blurs the line/distinction between fact and fiction.
  2 [  no obj  ] : to become unclear or difficult to see or remember
   I was so tired that my vision/eyes started to blur. [=I was not able to see clearly]
   The two events have blurred together in my mind.
  blurred  adj   [more ~; most ~]
   The writing is blurred [=blurry] but I think I can read it.
   The patient's symptoms include blurred vision.
   a blurred memory