Sui generis
Sui generis (pronounced  or ) is a term from Latin. It can be translated to Of (his/her/its) own kind. It basically means that something has VERY special characteristics. They are so special, that the thing cannot really be compared to anything else. It is used in various contexts. The term was invented by philosophers. What they originally wanted to say was that an idea is so specific as to be unique, that it cannot really be part of a broader concept.