IDK meaning refers to I'm not familiar with, while IDC refers to I'm not concerned about. These abbreviations most often appear in casual conversations online. IDK or IDC are two examples of acronyms that you might find in the text, email, and social media posts. IDK and cannot be interchangeable. Both can serve as a reply. IDK meaning is pronounced by saying each letter separately: ID-K. This word is not used in verbal conversations. Sometimes, however, you might hear IDK used as a joke or facetious.