Redletter is a rare term that refers to something special or remarkable. However, there are several antonyms for the word redletter, which are ordinary, mundane, boring, unremarkable, and common. These words describe items or events that are not special or noteworthy. For example, an ordinary day refers to a regular day with no particular event or activity that stands out. Mundane objects refer to everyday items that are not unique, such as a plain white mug. Boring activities are repetitive and tedious, and common experiences happen regularly with no exceptional or memorable aspect. In conclusion, antonyms for redletter describe things that do not stand out or have any particular significance.