MASS RUSH is a term used to describe a large group of people or animals moving quickly in the same direction. It is often used to describe a chaotic situation, such as a crowd of people running away from a dangerous situation. The term can also be used to describe a large group of animals, such as a herd of wildebeest, running across the African savannah. The crossword solution for MASS RUSH is STAMPEDE, which is an appropriate term for this phenomenon.