The term "cause celebre" is used to refer to a controversial issue or event that attracts a lot of attention from the media and the public. Antonyms for this phrase could include commonplace, mundane, unremarkable, or ordinary, which would describe events or issues that do not elicit such wide-scale attention or controversy. Other antonyms could be trivial, insignificant, or inconsequential, indicating that the issue or event in question is of little importance or relevance. These antonyms emphasize that cause celebre is a unique and rare occurrence that stands out in contrast to the everyday events and issues that we encounter.