Lambert m. Old High German lant, Old Saxon land 'land' + Old High German beraht, Old Saxon berht 'bright' from Proto-Germanic *berhtaz.
The name of a 7th C saint, a 9th C king of Italy and Holy Roman Emperor, the birth name of an 11th C pope, the name of an 11th C French saint, and the 12th C founder of the Beguines.