verb

• (intransitive) To become indistinct.
• (obsolete, transitive) To sully; to stain; to blemish, as reputation.
  "Sarcasms may eclipse thine own, / But cannot blur my lost renown."
• (graphical user interface, transitive) To transfer the input focus away from.
  "Then give this box focus to blur the first one: […]"
• (copyright law) To use a sign, image, expression, etc. sufficiently close to a trademarked one that it causes confusion between them.

noun

• (uncountable) Haziness, blurriness.
  "Unfortunately, a small artificial pupil also tends to increase the amount of diffraction somewhat, but this increase in blur is considerably smaller than the decrease that results from the control of other factors."
• (obsolete) A moral stain or blot.
  "[…]with her raillyng sette a great blurre on myne honesty"

adj

• (Singlish, Manglish) Lacking awareness; clueless or confused.
  "If a Singaporean gets frustrated at your stupidity, he can scold you for being blur as sotong (clueless as a squid)."