An antiseptic (Greek αντι, against, and σηπτικοζ, putrefactive) is a substance that prevents the growth and reproduction of various microorganisms (such as bacteria, fungi, protozoa, and viruses). Some are true germicides, capable of destroying the bacteria, whilst others merely prevent or inhibit their growth. The objective of antiseptics is to reduce the possibility of sepsis, infection, or putrefaction by germs. Antibacterials have the same objective but only act against bacteria. Antibiotics perform a similar function, preventing the growth or reproduction of bacteria within the body. Disinfectants operate on nonliving objects such as medical instruments.