Lisping, stuttering, stammering, lallation, nunnation and sigmatism, paragammacism and paralambdacism are but few of the locutory evils encountered, much too frequently in adolescents and adults. The fact that they are mostly amenable to treatment and may often be completely corrected, with proper attention and training, is something that needs to be more thoroughly impressed upon our educational bodies and sociologic reformers.
Source: wiktionary