Anamorphic, as used in describing the content of a late 20th century video
storage device called DVD, refers to a method of storing images with aspect
rations greater than 4:3 (the standard for televisions up to that time) and
utilize the maximum possible height of the image. The term "anamorphic" comes
from an earlier technology called "film", where a lens was used to squeeze a
wide image on to film, and a similar lens was then used to "unsqueeze" the
image and project it on to a wide screen. A similar process was done
electronically on some DVDs, thus providing a higher quality image for those
people who used Televisions with aspect ratios of 16:9. Video material that
was produced in other ratios, such as old movies produced in 2.35:1 ratio, were
often produced anamorphically on DVDs using the maximum possible number of
"lines" from the viewing device (television), but still showing black strips at
the top and bottom because the 16:9 ratio of the television is less than
2.35:1.
OED 2100 edition