blur
v.v. to make something look unclear or fuzzy, as if you cannot see it clearly. You use this when details become hard to distinguish.
v. to make or become indistinct, vague, or lacking in sharp definition. Transitive when applied to an image or object; intransitive when describing the loss of clarity.
The rain blurred the view from the window.
Tears blurred her vision so she could barely read the sign.
The rapid motion of the camera created a blur of light and color that captured the energy of the city at night.
From earlier blurre, probably an alteration of blear, from Middle English bleren, from Old English blerian (attested in āblered (“made bare, made bald”)), from Proto-West Germanic blaʀjan, from Proto-Germanic blazjaną (“to make pale”), from Proto-Germanic blasaz (“pale”). Compare Scots blore, bloar (“to blur, cover with blots”), Low German bleeroged (“blear-eyed”). More at blear.
The verb is transitive when taking a direct object (e.g., 'blur the lines'); it is intransitive when describing the state of becoming unclear.