The longest palindrome of the world exists in the Finnish language
According to the Guinness Book of Records, the longest palindrome in the world is saippuakivikauppias. The word is somewhat artificial but plausible and it means a dealer in lye or caustic soda. There are 19 letters in saippuakivikauppias.
Finnish works well in palindrome construction because it is a synthetic language that uses a lot of affixes attached to word stems. That makes for a lot of long words. But when it comes to the longest words found in a dictionary, German takes the cake. Take a look at the monster below:
Rindfleischetikettierungsüberwachungsaufgabenübertragungsgesetz
Let that sink in for a while.
It means a law that governs the transfer of beef labeling supervision tasks.