The term 'A Salt or Ester of Acetic Acid' can be summarized by two crossword solutions: ACETATE (7 letters) and borate (6 letters). ACETATE is a salt or ester of acetic acid, which is a weak organic acid found in vinegar. Borate is also a salt or ester of acetic acid, but it is composed of boron and oxygen atoms. Both ACETATE and borate are used in various industries, such as the textile industry, for dyeing and printing fabrics.