Mayenne

Mayenne (a department of Pays de la Loire, France); Mayenne (a right tributary of the Loire, in northwestern France, flowing through the departments of Orne, Mayenne and Maine-et-Loire)

The place is named after the River Mayenne, probably of Celtic origin, from Proto-Celtic *madyeti (“to burst, spread”); alternatively, from Latin madeo (“to be wet”). Both are ultimately from Proto-Indo-European *meh₂d- (“to be wet, moist”).