Synonym
A synonym is a word or phrase that means exactly or nearly the same as another word or phrase in the same language. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn (σύν) ("with") and onoma (ὄνομα) ("name"). An example of synonyms are the words begin, start, and commence. Words can be synonymous when meant in certain senses, even if they are not synonymous in all of their senses. For example, if we talk about a long time or an extended time, long and extended are synonymous within that context. Synonyms with exact interchangeability share a seme or denotational sememe, whereas those with inexactly similar meanings share a broader denotational or connotational sememe and thus overlap within a semantic field. Some academics call the former type cognitive synonyms to distinguish them from the latter type, which they call near-synonyms.
In the figurative sense, two words are sometimes said to be synonymous if they have the same connotation:
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name, although zoologists use the term somewhat differently. For example, Linnaeus was the first to give a scientific name (under the currently used system of scientific nomenclature) to the Norway spruce, which he called Pinus abies. This name is no longer in use: it is now a synonym of the current scientific name which is Picea abies.
Unlike synonyms in other contexts, in taxonomy a synonym is not interchangeable with the name of which it is a synonym. In taxonomy, synonyms are not equals, but have a different status. For any taxon with a particular circumscription, position, and rank, only one scientific name is considered to be the correct one at any given time (this correct name is to be determined by applying the relevant code of nomenclature). A synonym is always the synonym of a different scientific name and cannot exist in isolation. Given that the correct name of a taxon depends on the taxonomic viewpoint used (resulting in a particular circumscription, position and rank) a name that is one taxonomist's synonym may be another taxonomist's correct name (and vice versa).
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