In botanical nomenclature, a validly published name is a name that meets the requirements in the International Code of Nomenclature for algae, fungi, and plants for valid publication.[1] Valid publication of a name represents the minimum requirements for a botanical name to exist: terms that appear to be names but have not been validly published are referred to in the ICN as "designations".[1]
A validly published name may not satisfy all the requirements to be legitimate.[2] It is also not necessarily the correct name for a particular taxon and rank.[2]
Nevertheless, invalid names (nomen invalidum, nom. inval.) are sometimes in use. This may occur when a taxonomist finds and recognises a taxon and thinks of a name, but delays publishing it in an adequate manner. A common reason for this is that a taxonomist intends to write a magnum opus that provides an overview of the group, rather than a series of small papers. Another reason is that the code of nomenclature changes with time, and most changes have retroactive effect, which has resulted in some names that the author thought were validly published, becoming invalid.
The International Code of Nomenclature of Prokaryotes inherits the concept of a valid publication from the ICBN. To be considered valid, a name must be found in the Approved Lists of Bacterial Names, or is published in the International Journal of Systematic and Evolutionary Microbiology (formerly the International Journal of Systematic Bacteriology). The name must, of course, conform to the Code. Names that satisty the code but not found in these sources are effectively published as long as the journal is sufficiently recognized. Effective names can be made valid through "Validation List" publications made to the IJSEM. In addition, it is possible to validate a binomial name without the genus being validated.[3]
In zoology, the term "valid name" has a different meaning, analogous to (corresponding to) the botanical term "correct name".[1] [4] The term "validly published name" is more like (and it corresponds to) the zoological term "available name".