The product of an organism that destroys or weakens harmful microorganisms is called an antibiotic.

Here's a breakdown:

* Antibiotic: A substance produced by a microorganism (like bacteria or fungi) or synthesized chemically that can kill or inhibit the growth of other microorganisms, especially bacteria.

* Microorganisms: Tiny living things, such as bacteria, viruses, fungi, and protozoa, that are invisible to the naked eye.

* Harmful Microorganisms: These are microorganisms that can cause disease or infection in humans, animals, or plants.

Some common examples of antibiotics include penicillin, amoxicillin, and azithromycin.