There are numerous synonyms for the phrase "annually celebrated event". Some of the common ones include "annual tradition", "yearly ceremony", "recurring celebration", "annual festivity", "annual observance", "annual function", "annual ceremony", "annual holiday", "annual festival", and "annual occasion". All of these phrases imply that the event occurs on a yearly basis and is usually marked with festivities, ceremonies, or other special activities. No matter which synonym you choose to use, it is important to remember that these events hold significant meaning for the communities that celebrate them and are an important part of cultural and social heritage.