anorak

noun

1. A heavy weatherproof jacket with an attached hood; a parka or windcheater.

   “Don't ever use the hood on your anorak; and, if you do, for heaven's sake don't pull the string tight so that you peep out like a little baby in a siren suit.”

2. (UK, slang)A person with an unusual or obsessive interest in a niche subject, especially trains.

   “He has described himself as the uber-geek, an anorak's anorak, a standard bearer for fellow Star Trekkies everywhere, and his air of bland, amiable bafflement has served him remarkably well in a string of TV and film roles.”