nomen oblitum
/ˌnəʊmɛn əˈbliːtəm/ /ˌnəʊmən əˈbliːtəm/Taxonomy
noun
A Latin name which has been rejected despite being a senior synonym or senior homonym, through having been unused for a period specified in the appropriate code of biological nomenclature.
Origin
1960s. From scientific Latin nomen oblitum from classical Latin nōmen + oblītum, neuter singular of oblītus forgotten.