The crossword solution for the term 'FALL INTO DECAY' is ROT, which is an acronym for the process of decomposition caused by bacteria, fungi, and other organisms. This process is also known as biological decay and is a natural part of the cycle of life. ROT is responsible for the breakdown of organic matter, such as leaves, wood, and food, into simpler forms that can be used by other organisms. As materials decay, they release nutrients back into the environment, making them available for new growth.