A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature.
A semisystematic name or semitrivial name is a name that has at least one systematic part and at least one trivial part. 
Creating systematic names can be as simple as assigning a prefix or a number to each object (in which case they are a type of numbering scheme), or as complex as encoding the complete structure of the object in the name. Many systems combine some information about the named object with an extra sequence number to make it into a unique identifier.
Systematic names often co-exist with earlier common names assigned before the creation of any systematic naming system. For example, many common chemicals are still referred to by their common or trivial names, even by chemists.
In chemistry, a systematic name describes the chemical structure of a substance, thus giving some information about its chemical properties.
For IUPAC nomenclature, the Gold Book gives the definition:
"A name composed wholly of specially coined or selected syllables, with or without numerical prefixes; e.g. pentane, oxazole."  Here, trivial names can be systematic names or part of it, as they have become part of IUPAC nomenclature. For example, benzene (which is cyclohexatriene) or glycerol (which is trihydroxypropane).
There are standardized systematic or semi-systematic names for:
- chemical elements (following IUPAC guidelines)
- chemical compounds (following IUPAC guidelines)
- biological organisms, initiated by Carl Linnaeus
- astronomical objects and entities (administered by the International Astronomical Union)
- genes (following HGNC procedures)
- minerals (administered by the IMA)
- Biological classification
- Chemical element
- Chemical compound
- International scientific vocabulary
- List of Latin and Greek words commonly used in systematic names
- Naming scheme
- Numbering scheme
- Retained name
- Stedman's Medical Dictionary: semisystematic name
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "semisystematic name (semitrivial name)".
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "systematic name".