The term LIKE RAINFORESTS can be summarized by the word 'LUSH', which is a four-letter word. LUSH is an adjective that means 'luxuriantly rich and abundant in growth'. It is often used to describe rainforests, which are dense, tropical forests with a wide variety of plants and animals. Rainforests are known for their LUSH vegetation and biodiversity, making them some of the most diverse ecosystems on Earth.