The term 'fragrant substance' can be broken down into two crossword solutions: ESTER (5 letters) and Odorant (7 letters). An ESTER is an organic compound that is formed when an acid reacts with an alcohol, and it is known for its pleasant smell. Odorants are molecules that are responsible for the smells that we perceive, and they are often found in fragrant substances such as perfumes and essential oils.