The term 'Etiquette Authority' can be broken down into two crossword solutions: POST (4 letters) and MISSMANNERS (11 letters). POST is an acronym for 'Protocol, Officiating, Security, and Tactics', which are the four main components of etiquette. MISSMANNERS is the pseudonym of Judith Martin, an American author and journalist who wrote a syndicated column on etiquette. She is considered to be one of the most influential figures in the field of etiquette and is often referred to as the 'Etiquette Authority'.