Dictionary of Medieval Names
from European Sources

Gammo m. A pet form of any of various names beginning with Old High German gaman 'joy, merriment' or Old English gamol, old Norse gamall, Old Saxon *gamal from Proto-Germanic *gamalaz 'old, weak'.

France
Latin
1067x1086 Jammo (nom) CartNDSaintes XIV
Cite as: S.L. Uckelman. "Gammo". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2017, no. 1. http://dmnes.org/2017/1/name/Gammo.