Bokeh

(derived form Japanese Bokeaji "blur") is a photographic term referring to the appearance of out-of-focus areas in a image produced by a camera lens. Different lens bokeh produces different aesthetic qualities in out-of-focus backgrounds, which are often used to reduce distractions and emphasize the primary subject.
The term bokeh has appeared in photography books at lest since 2000 when digital camera flooded the international market.