Stinging; acerbic.
Having a sharp and stiff point.
Having a strong odor that stings the nose, said especially of acidic or spicy substances.
Having a strong taste that stings the tongue, said especially of hot (spicy) food, which has a strong and sharp or bitter taste.
dulled or intentionally blunt.
out of focus; blurry.
To sharpen (an image) by creating a blurred ("unsharp") negative as a mask, and then combining that mask with the original.