bokeh
A subjective aesthetic quality of out-of-focus areas of an image projected by a camera lens.
uncountable
Shooting with natural light, I used a long lens (200mm) to compress the space and slightly blur the background by photographing at a large open aperture (f/2.5). This resulted in gorgeous bokeh, putting the city into a blur while keeping the couple razor sharp.
Where it comes from
Learned borrowing from Japanese 暈(ぼ)け (boke, “blur”), the nominalized form of 暈(ぼ)ける (bokeru, “to blur”). The terminal -h, absent in the romanization boke, is a pronunciation guide so that it is not pronounced as /boʊk/ as it would be under standard English orthography. Contrast karate and karaoke, which have undergone sound changes. The term has been used since at least 1996, with the spelling bokeh introduced by editor Mike Johnston in the March–April 1997 issue of Photo Techniques magazine, Johnston writing “it is properly pronounced with bo as in bone and ke as in Kenneth, with equal stress on either syllable”.
Adapted from the Wiktionary entry bokeh (CC BY-SA 4.0).