Coadout () is a commune in the Côtes-d'Armor department of Brittany in northwestern France.
This village was known as "Coatnoüet ( = Coatvoüet), 1160-1167; Coetuout, 1382; Quoetvout, 1427; Coitbout, 1434; Coetbout, 1477; Coatout, 1481; Coetdout, 1535; Coadoult, 1581.
The name Coadout is typically Breton, "koad" meaning "wood" and possibly the Old French word "nouë" via the Gaulish word "nauda" meaning "marsh" or from the Old Breton "but", "bot" and "bod" meaning "residence". Another interpretation gives the radical -out the etymology of Illtud.
Inhabitants of Coadout are called Coadoutais in French.