The term 'REALLY BRIGHT' can be described by two crossword solutions: NEON (4 letters) and SMARTASAWHIP (12 letters). NEON is a type of gas that is used in fluorescent lighting, and is known for its bright, vivid colors. SMARTASAWHIP is an idiom that is used to describe someone who is very intelligent or quick-witted. Together, these two solutions provide a comprehensive description of the term 'REALLY BRIGHT'.