Senior Member

What is the difference in meaning between a 'germ' and a 'bacterium' ? I'm wondering specifically whether there could be 'good' and 'bad germs' or whether the word 'germ' is only negative.

I was thinking that perhaps bacterium is just a word for a type of microorganism and a germ is specifically a sort of 'bad' bacterium.

Thanks for help:)
  • Cypherpunk

    Senior Member
    US, English
    No, the word germ is used in a variety of ways, including the embryo of a plant seed and a small group of cells from which larger organisms grow. In fact, the human sperm and egg are both referred to as germs by some scientists. Germ is often associated with negative connotations due to its use in the phrase 'germ warfare', an older term for biological weapons and their use.


    Lapsed Moderator
    English-Ireland (top end)
    Germ is a very general term that can be applied to all kinds of things.
    Bacterium/ bacteria is much more specific.

    Germs and bacteria may be harmful, or not.


    Senior Member
    English (UK)
    Just to add to the above. The words bacterium/ bacteria/ bacterial would always be preferred in professional discussions e.g. "the bacterium causing this infection is..." would be correct in medical circles while "the germ causing this infection is..." would not do at all.


    Senior Member
    American English
    In just the medical context though, not zoology or botany or anything else, germ is always negative. The word germ never really appears in medical settings though since it is a lay term for any bacteria or virus that causes illness. A doctor might talk about germs with a patient that was averse to too much jargon. The place you hear about germs most is in ads for antimicrobial products.


    English--American (upstate NY)
    As living organisms that multiply within the body of a larger animal and, in so doing, make it ill or kill it, "germ" can refer to bacteria, viruses, or rickettsiæ (at least that's how I learned it; the rickettsiæ seem to be a family of bacteria). If you are told to cover your mouth when you sneeze, so as not to "spread germs," the reference could be to viruses as well as to bacteria.
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