Other forms: promulgations
Use the word promulgation when you're talking about an official announcement, like a newspaper story announcing a town's new regulations on trash and recycling services.
A public notice or announcement can be called a promulgation, though it's used more often to describe a government's declaration — often in the newspaper or on the radio — of new laws. If you want to sound especially formal or fancy, you can call your book club's notification of a venue change a promulgation. It comes from the Latin promulgare, "make publicly known," itself a combination of pro, "out," and mulgere, "to cause to come forth," or literally, "to milk."