* Formal: Her most endearing idiosyncrasy was her habit of humming while she worked.
* Informal: My grandpa has this strange idiosyncrasy of always wearing mismatched socks.
* Descriptive: The author's writing style is full of charming idiosyncrasies that make his work unique.
* Analytical: One of the company's biggest idiosyncrasies is its reluctance to embrace new technology.
* Humorous: My dog has a peculiar idiosyncrasy of chasing his tail until he gets dizzy.
Remember, "idiosyncrasy" refers to a peculiar or distinctive characteristic of a person or thing.