Glossary of Terminology

Term Definition
Agar A derivative of marine sea-weed, used as a solidifying agent in media.
Acid A substance with a pH less than 7.
Aerobic Grows in oxygen atmosphere.
Alkali Substance with a pH greater than 7.
Algicide A chemical agent which, under defined conditions, is capable of killing algae including their spores.
Amphoteric A class of surfactant, having both anionic and cationic properties.
Anaerobic Grows in oxygen free atmosphere.
Anionic A surfactant in which the surface-active agent has a negative charge.
Antimicrobial A substance capable of killing micro-organisms.
Antisepsis The destruction or inhibition of micro-organisms on living tissues having the effect of limiting or preventing the harmful results of infection. It is not a synonym for disinfection.
Antiseptic A chemical agent used in antisepsis.
Bacillus A rod shaped bacteria.
Bactericide A chemical agent which, under defined conditions, is capable of killing bacteria but not necessarily bacterial spores.
Bacteriostasis A state of bacterial population in which multiplication is inhibited.
Bacteriostat A chemical agent which under defined conditions induces bacteriostasis.
Base Another word for alkali, i.e. pH greater than 7.
Biocide A generalised term for a chemical agent capable of killing or inactivating micro-organisms. It embraces the more specific terms algicide, bactericide, fungicide, sporicide and virucide (see also germicide).Note. Pesticides are not considered to be biocides.
Cationic A surfactant in which the surface-active agent has a positive charge.
Chemical Sterilising Agent A chemical agent which, under defined conditions, leads to sterilisation.
Chlorhexidine A bisphenol compound used as an antiseptic and disinfectant.
Chlorine A member of the halogen group of elements. Frequently, but usually, incorrectly used to define the active species in, e.g. solutions of sodium hypochlorite.
Coccus A spherical bacterium.
Disease Any change from a general state of good health.
Disinfectant A chemical agent which under defined conditions is capable of disinfection.
Disinfection The destruction of micro-organisms, but not usually bacterial spores: it does not necessarily kill all micro-organisms, but reduces them to a level acceptable for a defined purpose, for example, a level which is harmful neither to health nor to the quality of perishable goods.
DNA Deoxyribonucleic acid. Protein that contains instructions for building other proteins.
Fumigation Exposure of enclosed spaces to action of gaseous or vapour phase disinfectants or sterilants.
Fungus A group of diverse unicellular and multicellular microorganisms (pl. fungi)
Fungicide A chemical agent which under defined conditions is capable of killing fungi including their spores.
Fungistasis A state of fungal population the development of which is inhibited.
Fungistat A chemical agent which under defined conditions induces Fungistasis.
Genus A group of closely related species.
Germ A general term which should be avoided. A micro-organism which can be harmful.
Germicide A general term which should be avoided. An agent under defined conditions, which is capable of killing germs.
Glutaraldehyde A broad spectrum biocide used as an active ingredient in formulated disinfectants.
Gram-Negative Gram-Negative bacteria do not have thick cell walls, and have a lipid membrane, making them harder to lyse.  Will give a negative result in a gram stain test.
Gram-Positive Gram-Positive bacteria have thick, polar cell walls that are easier to lyse. Will give a positive result in a gram stain test.
Gram Stain Stain technique used to classify bacteria into two groups: Gram negative or Gram positive.
Halogens A group of chemicals consisting of Fluorine, Chlorine, Iodine and Bromine (plus Astatine and Tennesine). Chlorine and iodine can be found in a number of disinfectants.
Hydrogen Peroxide A bleaching / oxidising agent used as a disinfectant.
Hypochlorite Usually sodium hypochlorite, but also calcium hypochlorite, solutions of hypochlorite are oxidising disinfectants producing the biocidally active hypochlorite anion and hypochlorous acid.
Iodine A halogen with similar properties to chlorine, but more stable and less reactive.
Iodophor Iodine in solution of surfactant with stabiliser.
Lysis The process of lysing a cell.
Lyse To break open a cell’s membrane.
Media A nutrient rich solid or liquid (agar or broth) used to grow micro-organisms.
Microbe An alternative expression for micro-organism.
Micro-organism A microscopic entity capable of replication. It includes bacteria, viruses and the microscopic forms of algae, fungi and protozoa.
Motile Describes organisms which can move independently.
Mould Any fungus that forms visible mycelia growth.
Mycelium A visible mass of tangled filaments of fungal growth.
Nucleic Acids An organic compound composed of nucleotides DNA and RNA.
Oocyst An oval body in the reproduction cycle of certain protozoa.
Pathogen An organism that causes disease. Can be animals, plants or micro-organisms.
Peracetic acid Acid produced by combination of acetic acid and hydrogen peroxide. A highly effective biocide.
Phenol Also known as carbolic acid, a phenyl alcohol derived from coal tar. Used as a disinfectant.
Preservation Maintaining numbers of micro-organisms at low levels i.e. low enough to make food safe to eat or to prevent spoilage.
Protozoa Unicellular micro-organisms. Classified in the Animal Kingdom.
QAC / Quat Quaternary ammonium compounds. Cationic surfactants with bactericidal but weak detergent properties.
RNA Ribonucleic acid. Involved in protein synthesis.
Sanitisation A term used mainly in the food and catering industry. A process of both cleaning / disinfecting utensils, equipment and surfaces.
Sanitiser A chemical agent used for sanitisation.
Sanitize U.S. spelling of sanitise.
Somatic Refers to the “body” or main part of a cell. Does not include reproductive structures such as spores.
Species Fundamental rank of the classification system. (Two or more species grouped together are classed as a genus).
Spirochete A twisted bacterial rod with a flexible cell wall containing axial filaments for motility.
Spore A highly resistant structure formed from somatic cells in several genera of bacteria. E.g. Bacillus.  Also, a reproductive structure formed by fungi.
Sporicide A chemical agent which, under defined conditions, is capable of killing bacterial spores.
Sterile Free from all living micro-organisms.
Sterilisation A process which renders an item sterile.
Sterilising agent An agent or combination of agents which under defined conditions leads to sterilisation.
Sterilize U.S. spelling of sterilise.
Surfactant A surface active agent.
Toxin A poisonous substance produced by a species of micro-organism.
Vibrio A form of bacteria occurring as a curved rod.
Virucide A chemical agent which, under defined conditions, is capable of killing or inactivating viruses.
Virus A non-cellular entity consisting of protein and nucleic acid. Can only replicate after entry into specific types of living cell. 
Zoonosis Any disease which can be transmitted from animal to man and vice-versa.