Platonist

noun3

1. •
   A member of the philosophical school of thought established by Plato; a believer in Platonism.

   • [St Augustine of Hippo] became of a Maniche, and of a platoniste a good christian. — 1549
2. •
   One who holds similar beliefs, particularly that abstract ideas are real.
3. •
   (no longer used, rare) A platonic lover.