A peculiarity, especially a verbal one; a mannerism.
Origin
Mid 19th century; earliest use found in Clement Ingleby (1823–1886), literary scholar. From Byzantine Greek ἰδιασμός peculiarity from Hellenistic Greek ἰδιάζειν to be peculiar + -μός, suffix forming nouns.
Definition of idiasm in US English:
idiasm
nounˈɪdɪaz(ə)m
A peculiarity, especially a verbal one; a mannerism.
Origin
Mid 19th century; earliest use found in Clement Ingleby (1823–1886), literary scholar. From Byzantine Greek ἰδιασμός peculiarity from Hellenistic Greek ἰδιάζειν to be peculiar + -μός, suffix forming nouns.