philodox
A person with an excessive interest in his/her own opinions.
And no people are lesse Philosophers and more foolish, than Platoes Philodoxes, or lovers of their owne opinions.
Where it comes from
From Middle French philodoxe, from Ancient Greek φιλόδοξος (philódoxos, “opinion-loving”), compound of φίλο- (phílo-, “beloved”) + δόξα (dóxa, “glory; opinion”).
Adapted from the Wiktionary entry philodox (CC BY-SA 4.0).