The term 'slimy substance' can be described by four different words: GOO (3 letters), OOZE (4 letters), MUCUS (5 letters), and GUCK (4 letters). GOO is a sticky, viscous liquid that is often used to describe a slimy substance. OOZE is a slow, steady flow of a liquid, which is also often used to describe a slimy substance. MUCUS is a thick, slippery secretion produced by the body, which is also often used to describe a slimy substance. Finally, GUCK is a slang term for a slimy substance. All of these words are commonly used to describe a slimy substance.