Danny asked “What term would photographers use to describe the quality of blurred part of the photo?”
Danny: The term would be Bokeh, this term really refers to the quality of the blur but is most often associated with what is calledÂ specular highlights. you can find out more about Bokeh here.
You may also wish to research more about Depth of FieldÂ (DOF) which is where the photographer purposely (or in come cases accidentally) introduces blur to the image to focus the viewers attention to the location they wish to highlight.
For your easy reference the image at the top of this article shows Bokeh and one below this sentence shows DOF where the tip of the pen and fingers are in focus and the rest of the hand is distinctly out of focus.