Dictionary of Medieval Names
from European Sources

Seaborn m. Old English 'sea, lake' + Old English bera, *beorn 'bear'.

Ireland
Latin
fin12thC Seaborn (gen) MunDocIr III, p. 10
Cite as: S.L. Uckelman. "Seaborn". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2016, no. 4. http://dmnes.org/2016/4/name/Seaborn.