in biological classification, system of naming organisms. The species to which the organism belongs is indicated by two words, the genus and species names, which are Latinized words derived from various sources. This system, which is called the Linnaean system of binomial nomenclature, was established in the 1750s by Carolus Linnaeus (Linnaeus, Carolus). Subsequent to the work of Linnaeus, a proliferation of binomial names took place as new species were established and higher taxonomic categories were formed, with the result that by the late 19th century there was much confusion in the nomenclature of many groups of organisms. In the 20th century, the establishment of rules by international committees in the fields of zoology, botany, bacteriology, and virology has done much to clarify the situation.

Contrary to the widely held view that scientific names, once assigned, are fixed and universal in their use, continuing research on the relationships of organisms and probing into the history of names, coupled with disagreements among scientists on the validity of certain names, results in multiple names being applied to some well-known species. The international rules, however, are gradually bringing stability to the taxonomy of many groups through the minimizing of name changes, the use of standard methods of establishing new names, and the functioning of respected committees to arbitrate controversies.