Plonéour-Lanvern (French pronunciation: [plɔneuʁ lɑ̃vɛʁn]; Breton: Ploneour-Lanwern) is a commune in the Finistère department of Brittany in north-western France.

The name Plonéour means in Breton Saint Enéour's plou (parish), to which was added the name of Lanvern (which comes from the Breton lan (hermitage) and of the name Wern or Guern which means swamp of alders) when this former(old) parish was connected with the municipality recently created by Plonéour in 1793.

The legend says that the menhir which raises itself (draws up itself) on the central place(square) of Plonéour-Lanvern would be the mast of the boat which would have brought saint Enéour of Great Britain in Cornouaille.

Flowing initially in the direction of the southeast, she turns then due south, passing between Peumerit and Plonéour-Lanvern on the West and Tréméoc in the East.

Downstream to this stretch of water the small coastal river takes a course in the direction of the southeast until Pont-l'Abbé.