Côtes-d'Armor (Aodoù an Arvor in Breton and departaman dé Caouwt 'd'Armor in Gallo) (22) is the name of a french department located in Brittany.
The department takes its name
* Breton word of former Armor, whose geographical term Armorica is, in modern Breton an Arvor (the sea), as opposed to Argoad or Argoat (forested country, by extension, inland), a hand,
* Gallo's "Caouwt 'd'Armor": "Caouwt" meaning "side"
* Of its former name, the Côtes-du-Nord, on the other.