a microorganism such as a virus or a bacterium that causes disease;
e.g. She is studying the germ that causes an illness in horses.
(noun)
a small portion of living matter that is capable of developing into an organism or one of its parts, such as the embryo of a plant seed like a cereal grain;
e.g. The germ will not develop properly without the required nutrients.
(noun)
the beginning or origin of something, an initial stage from which it develops further;
e.g. He had a germ of a plan on his mind, and he intended to work with it further.