prerhotic

/P R R HH AA1 T IH0 K/
adjective
  1. 1

    (linguistics, rare) Occurring before the letter ⟨r⟩ or before any one of the sounds that letter tends to represent (e.g., [r], [ɽ], [ɹ], [ɻ], [ʀ], [ʁ], etc.).