Dictionary of Medieval Names
from European Sources

Ratelm m. Old Saxon rād, Old High German rāt 'counsel, advice' + Old High German, Old Saxon helm 'helmet'.

France
Latin
700 Ratelmo (abl) DCEL-2 XIV
Cite as: S.L. Uckelman. "Ratelm". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2016, no. 4. http://dmnes.org/2016/4/name/Ratelm.