The term 'BRIGHT LINE' can be broken down into two crossword solutions, RAY and 3 letters. RAY is a word that means a narrow beam of light or radiation, such as a laser beam. The 3 letters refer to the scientific term 'EMR, ' which stands for electromagnetic radiation. This type of radiation is emitted by stars and other celestial bodies, and is also used in many forms of communication. Together, these two solutions form the term 'BRIGHT LINE, ' which is a term used to describe the visible spectrum of light that is visible to the human eye.