1. 模糊形状；模糊的区域
    A blur is a shape or area which you cannot see clearly because it has no distinct outline or because it is moving very fast.

    e.g. Out of the corner of my eye I saw a blur of movement on the other side of the glass...
           从眼角余光中我看到玻璃的另一边隐约有东西在移动。
    e.g. Her face is a blur.
           她的脸模糊不清。

2. （使）变得模糊不清
    When a thing blurs or when something blurs it, you cannot see it clearly because its edges are no longer distinct.

blur的反义词

    e.g. This creates a spectrum of colours at the edges of objects which blurs the image...
           这在物体的边缘形成了一道色谱，使图像变得模糊不清。
    e.g. If you move your eyes and your head, the picture will blur.
           如果你的眼睛或头动了，图像就会变得模糊不清。

3. 使（想法、区别等）模糊；使（想法、区别等）不明晰
    If something blurs an idea or a distinction between things, that idea or distinction no longer seems clear.

blur

    e.g. ...her belief that scientists are trying to blur the distinction between 'how' and 'why' questions...
           她认为科学家们试图模糊“如何”和“为什么”这两类问题之间的区别
    e.g. The evidence is blurred by central banks' reluctance to reveal their blunders.
           由于中央银行不愿意公开自己的愚蠢错误，证据并不清楚。

4. （使）（视力）模糊；（使）看不清楚
    If your vision blurs, or if something blurs it, you cannot see things clearly.

    e.g. Her eyes, behind her glasses, began to blur...
           她藏在眼镜后面的双眼变得模糊起来。
    e.g. Sweat ran from his forehead into his eyes, blurring his vision.
           汗水从额头流到了眼睛里，模糊了他的视线。