Spore is a type of reproductive cell that is produced by some plants, fungi, and bacteria. It is a single-celled organism that can survive in harsh environments and is capable of reproducing asexually. The term 'spore' is derived from the Greek word for SEED. The four letter crossword solution GERM refers to a spore's ability to germinate and grow into a new organism. The three letter crossword solution SAC refers to the protective outer covering of a spore, which is known as a spore SAC. The four letter crossword solution SEED refers to the fact that a spore is often referred to as a 'microscopic SEED'.