defective pronunciation of sibilant sounds.
Origin of sigmatism
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for sigmatism
Historical Examples of sigmatism
Sigmatism and parasigmatism and paralambdacism are strongly marked.The Mind of the Child, Part II
Online Etymology Dictionary, © 2010 Douglas Harper