The crossword solution for the term 'Holiday and Days' is INNS. INNS stands for International Nomenclature of Seasonal and Holiday Dates, which is a system used to identify holidays and days of observance around the world. This system was developed by the United Nations in order to standardize the way in which holidays and days of observance are identified and tracked. The system is used by governments, businesses, and other organizations to ensure that holidays and days of observance are recognized and respected in a consistent manner.