Phylum Nematoda, commonly known as roundworms, is a group of unsegmented, elongated, and cylindrical worms that are found in diverse habitats across the world. While they are commonly known as roundworms, they are also referred to as nematodes, threadworms, or whipworms. The word nematode comes from the Greek words "nema" and "odes" which means thread and like, respectively. Threadworm is derived from their thread-like appearance, while whipworms have a whip-like appearance due to the curved end of their bodies. Additionally, they are also referred to as filarias, pinworms, and hookworms based on their specific morphological features and parasitic mode of living. Regardless of the name used to refer to them, nematodes play a significant role in various ecosystems and human health.