资料来源 : Webster's Revised Unabridged Dictionary (1913)

Betacism \Be"ta*cism\, Betacismus \Be`ta*cis"mus\, n.
   Excessive or extended use of the b sound in speech, due to
   conversion of other sounds into it, as through inability to
   distinguish them from b, or because of difficulty in
   pronouncing them.