In science, a common name is any name by which a species or other concept is known that is not the official scientific name.

Biological common names

In biology, a common name of a species is any name other than its scientific name, i.e., in binomial nomenclature. Every binomial is nominally in the Latin language, so every name of an organism in English, Swedish, Japanese, or any other language besides botanical Latin is a common name, whether or not it corresponds neatly to a scientific name. Our everyday names for plants and animals like rose, oak, squirrel, and cat are example of common names.

Many common names are ambiguous when used in a scientific context. Names like sardine or deer are applied to dozens of different species, though those names are perfectly adequate in their original domains of use (fishing and hunting).

However, in some taxa, such as the birds, individual species have official common names. Such official common names are chosen by a governing body and typically are modeled after Latin binomial names; usually they are capitalized. An example of an official common name is Red-tailed Hawk. It is debatable whether official common names are actually "common", since they are created systematically, can be changed by fiat, and do not necessarily correspond to commonly used layperson's names. Official common names have little scientific weight, are not recognized internationally, and are not a substitute for scientific names. Scientists mostly use them when communicating with non-scientists who might be intimidated by scientific names. Botanists do not maintain official common names for plants, but some government agencies do. Botanists generally do not capitalize any common names (except in cases where the name includes a proper noun which retains its capitalization such as "Chinese piscache", "American ginseng", etc).

Scientific names sometimes become the common names through extensive daily use by nonscientists, for instance in gardening. Familiar names like begonia, dahlia, gladiolus, and rhododendron originated as the names of genera. Gardeners often continue to use these names even if the scientific name of the plant changes. For example, geranium (gardeners' common name) is not the same as Geranium (genus) but is in fact called Pelargonium by botanists. Note that such ex-Latin names are not capitalized or written in special script.

Chemical common names

In chemistry, the IUPAC nomenclature, a convention on systematic names, a common name is a name from which a structural formula can be drawn, that doesn't follow the systematic naming procedure.