Rhotacism may refer to several phenomena related to the usage of the consonant r (whether as an alveolar tap, alveolar trill, or the rarer uvular trill). the excessive or idiosyncratic use of the r; conversely, the inability or difficulty in pronouncing r. the conversion of another consonant, for example, intervocalic Old Latin s, into Classical Latin r. The term comes from the Greek letter rho, denoting "r". Orthoepy In medicine, rhotacism's the inability or difficulty in pronouncing the sou… (More on Rhotacism)