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 called specular highlights. you can find out more about Bokeh here.
You may also wish to research more about Depth of Field (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.
Jeremy is a consultant, educator and photographer based in the Caribbean. He shoots an eclectic range of material, but his favorite subjects are urban and seascapes, people and aircraft. He mixes his love of technology and travel with photography. Following a brief post college hiatus he picked up a camera again in 2003 and has been shooting ever since. You may view his work on his website