1888, "lisping difficulty in pronouncing 'S,'" from combining form of sigma + -ism. As "use or recurrence of 'S'" from 1889. Also sigmatismus.
Entries linking to sigmatism
sigma
18th letter of the Greek alphabet, corresponding to Latin S; the name is a metathesis of Hebrew samekh. In uncial writing, shaped like an S or a C.
-ism
word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.