Pierre, de France, Seigneur de Courtenay - Pierre de Courtenay

PIERRE de France ([1126]-Palestine 10 Mar [1180/10 Apr 1183]). William of Tyre names him as brother of Louis VII King of France, when recording his arrival in Palestine in 1179[406]. He succeeded as Seigneur de Courtenay, by right of his wife. "Petrus regis frater et Curtiniacensis dominus" donated property to the abbey of Fontaine-Jean by charter dated 1170, with the support of "uxor mea Isabel et primogenitus meus Petrus"[407]. The necrology of La Cour-Dieu records the death “VI Id Mar” of “Petrus de Curtiniaco”[408]. http://fmg.ac/Projects/MedLands/CAPET.htm#LouisVIdied1137B

Seigneur is the French for "lord" and as Sharon mentioned it before he was Lord of Courtenay by his mariage to Elisabeth heiress of Courtenay.
http://roglo.eu/roglo?lang=fr;i=1368586