Microorganism vs. Pathogen — What's the Difference?

A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or a colony of cells. The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India.

In biology, a pathogen (Greek: πάθος pathos "suffering", "passion" and -γενής -genēs "producer of") in the oldest and broadest sense, is any organism that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.

An organism or infectious agent of microscopic or submicroscopic size, especially a bacterium or protozoan.

An agent that causes disease, especially a virus, bacterium, or fungus.

(microbiology) An organism that is too small to be seen by the unaided eye, especially a single-celled organism, such as a bacterium.

Any organism or substance, especially a microorganism, capable of causing disease, such as bacteria, viruses, protozoa or fungi. Microorganisms are not considered to be pathogenic until they have reached a population size that is large enough to cause disease.

Any microscopic form of life; a form of life too small to be seen by the naked eye; - particularly applied to bacteria, protozoa, yeasts, and similar organisms, esp. such are supposed to cause infectious diseases.

Any microorganism which causes disease; a pathogenic organism; an infectious microorganism; a bacterium, virus, or other agent which can cause disease by infection; - opposed to zymogene. The spelling pathogene is now archaic.

Any organism of microscopic size

Any disease-producing agent (especially a virus or bacterium or other microorganism)