The word schadenfreude, meaning "pleasure derived from others' pain", suddenly became extremely popular after its use in a 1991 episode of The Simpsons and has been prominent in our vernacular ever since. The noun was in use since the 1850s, but a lot of the early attestations just provided it as an example of interesting German word - it wasn't seamlessly integrated into English text until the start of the twentieth century. In German, the word is a bit of an etymological oxymoron, coming from schaden, meaning "harm", and freude, meaning "joy". Schaden is from Old High German scado, or "damage". That, through Proto-Germanic skatho, came from Proto-Indo-European sket, with the same definition. Freude traces to Proto-Germanic frawaz, meaning "joy", which came from PIE prew, "to hop". What a cool word!
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.