The term 'small parasite' can be summarized by the crossword solution of 'MITE, ' which is a four-letter word. Mites are tiny arthropods that are related to spiders and ticks. They are usually found in soil, dust, and other organic matter, and they feed on plants, fungi, and other small organisms. Mites can also be parasites of humans and animals, causing skin irritation and other health problems.