What does sharpness mean?

Sharpness, sometimes called "sharpness", is an index that reflects the plane sharpness and edge sharpness of an image. If the definition is increased, the detail contrast on the image plane is also higher and looks clearer. For example, in the case of high definition, not only the wrinkles and spots on the face on the screen are clearer, but also the protrusions or depressions of facial muscles can be vividly displayed.