Submitted NameRevisions Save Gender Masculine Usage Welsh Mythology Pronounced Pron. NEE-shehn [key·IPA] Other Forms FormsNissyen Edit Status Status [show contributorshide contributors] Added 12/27/2019 by Frollein Gladys Edited 11/27/2020 by Frollein Gladys Meaning & History Nisien is a figure in Welsh mythology, the son of PENARDDUN and Euroswydd and twin brother of Efnysien.