1. A part of an organism that is typically self-contained and has a specific vital function, such as the heart or liver in humans.
For some time, the Guinness Book people thought that all the world's oldest (biological) organs were contained within one person: a 122-year-old French woman named Jeanne Calment, who died in 1997. (There may have been older people in the world, but Calment had the papers to prove her age.) Recently, however, a comparatively sprightly 80-year-old fellow in Norway did her one better: it was discovered that Bernt Aune had a cornea transplant in 1958, an organ that had been harvested from the cadaver of an elderly man born in 1885 -- making Aune's cornea 123 years old (last year anyway) -- the oldest in the world. So how well does Aune see through his antique cornea? "My vision's not great," he says.
2. A large musical instrument having rows of tuned pipes sounded by compressed air, and played using one or more keyboards to produce a wide range of musical effects.
The world's oldest still-functional pipe organ was built around 1435, and is housed in the Basilica de ValÃ¨re in Switzerland, which is about a century older than the organ. You can hear the organ played once a year, during the aptly named Festival of the Old Organ.
3. A medium of communication, esp. a newspaper or periodical that serves a particular organization, political party, etc. : the People's Daily, the official organ of the Chinese Communist Party.
The world's oldest still-operating newspaper is generally agreed to be Sweden's Post-och Inrikes Tidningar ("Post and Domestic Newspaper"), founded by Queen Christina in 1645 as the Ordinari Post Tijdender ("Regular Mail Tidings"). Its original editors were postmasters, who circulated about the country more than almost anyone else, and would compile any newsworthy tidings they came across and send them to the newspaper, which was then distributed and posted on public notice boards across the country. It was the largest and most important newspaper in Sweden for centuries, but in 1922 heavy competition forced it out of its traditional business model, and it began to publish only governmental, corporate and legal announcements. In 2007, the world's oldest newspaper went green, and is now published online only. If you can read Swedish, you can read it here. Compare that to the 1645 edition: