Priority is a principle in biological taxonomy by which a valid scientific name is established based on the oldest available name. It is a decisive rule in botanical and zoological nomenclature to recognise the first binomial name (also called binominal name in zoology) given to an organism as the correct and acceptable name.[1][2] The purpose is to select one scientific name as a stable one out of two or more alternate names that often exist for a single species.[3][4]
The International Code of Nomenclature for algae, fungi, and plants (ICN) defines it as: "A right to precedence established by the date of valid publication of a legitimate name or of an earlier homonym, or by the date of designation of a type."[5] Basically, it is a scientific procedure to eliminate duplicate or multiple names for a species, for which Lucien Marcus Underwood called it "the principle of outlaw in nomenclature".[6]