Binomial nomenclature

Definition

The formal system of naming species using a two-part Latinized name consisting of the genus (capitalized) followed by the specific epithet (lowercase), together designating a single species uniquely worldwide. Governed by the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Nomenclature for algae, fungi, and plants (ICNafp) for botanical organisms. The complete name is italicized (or underlined in manuscript) and often abbreviated after first mention.

Etymology

Latin binomius 'having two names' + nomenclatura 'system of naming'

Example

The honey bee is named Apis mellifera Linnaeus, 1758; 'Apis' is the genus shared with other honey bees, while 'mellifera' distinguishes this particular species.

Synonyms

• binary nomenclature
• binominal nomenclature
• binomial system

Related Terms

• trinomial nomenclature
• Genus
• specific epithet
• Scientific name
• International Code of Zoological Nomenclature
• Type specimen
• homonym
• synonym

Usage Notes

Specialists in zoology follow ICZN spelling 'binominal nomenclature' (with 'n'), though 'binomial' predominates in general and botanical usage. The two terms are often treated as synonymous in practice. The binomial alone does not indicate subspecies; trinomial nomenclature adds a third epithet for subspecific ranks. The original describer and year may be appended (e.g., 'Linnaeus, 1758') but are not part of the binomial itself.