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 agent, whether a living organism or abiotic agent, that induces disease.
An organism which may cause disease.
A microorganism that causes disease; may be bacterial, viral, fungal, chlamydial, rickettsial, or parasitic.