rhotacism

noun3

1. •
   The inability to pronounce the letter R; derhotacization.

   • From the analysis of Kana writings, hypothesizes that the inability to establish a stable… […] The correction of rhotacism by means of an electric vibrator. — 1976
2. •
   A linguistic phenomenon in which a consonant changes into an R; rhotacization.
3. •
   An exaggerated use of the sound of the letter R.