Welcome to the Word of the Day from AskOxford:
[FLEM-unz-firth] an Old English law term for the crime of harboring a banished person.
It's a corruption of an Old English term that literally means 'entertainment of fugitives', which makes you wonder that if the fugitives aren't having a really good time, is it still a crime? What if they're only smiling politely?
Also, GIP, courtesy of truepenny.