from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An agent that causes disease, especially a living microorganism such as a bacterium or fungus.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. 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.
from the GNU version of the Collaborative International Dictionary of English
- n. 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.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. any disease-producing agent (especially a virus or bacterium or other microorganism)
From patho- + -gen. (Wiktionary)