An anorak is a type of heavy jacket with a hood, generally lined with fur or fun fur, so as to protect the face from a combination of sub-zero temperatures and wind. The word "anorak" is British, the same sort of jacket being called a parka in the United States and Canada. Originally a parka was a pull-over jacket without an zipper, button or frogged opening, but the distinction is now largely lost.
Originally invented by the Inuit, who needed clothing which protected them from windchill and wet, while hunting and kayaking in the arctic region. Underneath the anorak the Inuit wear warm clothes. Inuit anoraks have to be regularly soaked with train oil (fish oil) to keep their water resistance. Today, the jacket is named after it because it attempts to be just as waterproof.
In British slang, anorak has come to mean "geek" or "nerd", originally from their use as the invariable wear of train spotterss, and then by extension to refer to anyone with an unfathomable interest in detailed information regarded as boring by the rest of the population - aided by the intuition that only a geek would wear something so terminally unfashionable.
Anorak is also the name of a British parody on a tabloid. Its slogan is "Keeping an eye on the tabloids". Some claim Anorak is a real newspaper.