The term 'clear blue SKY' can be represented by two crossword solutions: ETHER (5 letters) and OUTOFA (6 letters). ETHER is a colorless, odorless, tasteless gas that makes up the majority of the Earth's atmosphere. It is also known as the 'upper air' or 'SKY'. OUTOFA is an acronym for 'Out of the Air', which is a phrase used to describe a clear, cloudless SKY. Both of these terms are used to describe a beautiful, sunny day with no clouds in the SKY.