The term 'PEST' is a general term used to describe any type of insect or animal that causes damage to crops, property, or health. In this case, the crossword solutions for the term 'termite or GNAT' are both four-letter words: 'MITE' and 'GNAT'. Mites are small arthropods that feed on organic matter, while gnats are small flies that feed on plant nectar and other liquids. Both termites and gnats can be considered pests, as they can cause damage to crops, property, and health.