In linguistic terminology, compound words that are formed with suffix -onym are most commonly used as designations for various onomastic classes.
[1][2] For example, onomastic terms like toponym and linguonym are typical classical (or neoclassical) compounds, formed from suffix -onym and classical (Greek and Latin) root words (Ancient Greek: τόπος / place; Latin: lingua / language).
In the compounds like ananym and metanym, the correct forms (anonym and metonym) were pre-occupied by other meanings.
Other, late 20th century examples, such as hypernym and characternym, are typically redundant neologisms, for which there are more traditional words formed with the full -onym (hyperonym and charactonym).
In many cases, two or more words describe the same phenomenon, but no precedence is discernible (e.g., necronym and penthonym).