Xerography or electrophotography is a dry photocopying technique. Its fundamental principle was invented by Hungarian physicist PÃ¡l SelÃ©nyi and based on SelÃ©nyi's publications Chester Carlson applied for and was awarded U.S. Patent 2,297,691 on October 6, 1942. The technique was originally called electrophotography.
A retrospective, generally, is a look back at events that took place, or works that were produced, in the past. As a noun, retrospective has specific meanings in medicine, software development, popular culture and the arts. It is applied as an adjective, synonymous with the term retroactive, to laws, standards, and awards.
retroactive adjective. âº If a âlaw or âdecision, etc. is retroactive, it has âeffect from a âdate before it was âapproved: the first British âlaw to have retroactive âeffect. retroactively adverb uk us /-li/ âº The âcourts cannot âapply a new ârule retroactively. adverb uk us /-li/.