blur (n.)youdaoicibaDictYouDict
1540s, "smear on the surface of writing;" perhaps akin to blear. Extended sense of "confused dimness" is from 1860.
blur (v.)youdaoicibaDictYouDict
1580s, and thus probably from blur (n.), but the dates are close and either might be the original. Related: Blurred; blurring.