sigmatism

From sigma +‎ -ism. sigmat- is the stem form of sigma, as seen in sigmatic.

• IPA^(key): [sɪɡmʌtɪzm]

sigmatism (countable and uncountable, plural sigmatisms)

1. A lisp.
2. Defective pronunciation of sibilant sounds.
   • 2007 October 30, C. Claiborne Ray, “Whence the Whistle?”, in New York Times‎:

     The flaw in pronouncing a sibilant S, which speech therapists call sigmatism, can follow even minor changes to the way the tongue aligns with the teeth.

Borrowed from French sigmatisme.

sigmatism n (uncountable)

1. sigmatism