What word or phrase does your mother always say?
mid-15c., "bud, sprout;" 1640s, "rudiment of a new organism in an existing one," from Middle French germe "germ (of egg); bud, seed, fruit; offering," from Latin germen (genitive germinis) "sprout, bud," perhaps from PIE root *gen- "to beget, bear" (see genus). The older sense is preserved in wheat germ and germ of an idea; sense of "seed of a disease" first recorded 1803; that of "harmful microorganism" dates from 1871. Germ warfare recorded from 1920.
A small mass of protoplasm or cells from which a new organism or one of its parts may develop.
A microorganism, especially a pathogen.
A microscopic organism or agent, especially one that is pathogenic, such as a bacterium or virus.
Our Living Language : The terms germ and microbe have been used to refer to invisible agents of disease since the nineteenth century, when scientists introduced the germ theory of disease, the idea that infections and contagious diseases are caused by microorganisms. Microbe, a shortening and alteration of microorganism, comes from the Greek prefix mikro-, "small," and the word bios, "life." Scientists no longer use the terms germ and microbe very much. Today they can usually identify the specific agents of disease, such as individual species of bacteria or viruses. To refer generally to agents of disease, they use the term pathogen, from the Greek pathos, "suffering," and the suffix -gen, "producer." They use microorganism to refer to any unicellular organism, whether disease-causing or not.