A PATHOGEN is an 8-letter term for a disease-causing microorganism, while a GERM is a 4-letter term for the same. Pathogens and germs are microscopic organisms that can cause illnesses in humans, animals, and plants. These microorganisms can be bacteria, viruses, fungi, or parasites. They can spread through contact with an infected person or animal, contaminated food or water, or contact with contaminated surfaces.