1. A language expression or grammatical construction that is peculiar to a particular language and cannot be understood from the literal meaning of its words; an idiom.
Usage: Often used in linguistics and language study contexts.; Somewhat archaic; 'idiom' is the more common modern term.
2. Extreme stupidity or foolishness; the state or quality of being an idiot.
Usage: Archaic or offensive; rarely used in modern English.; Considered derogatory.

Examples

• The phrase 'raining cats and dogs' is an idiotism that native speakers understand but learners often find confusing.
• In linguistics class, we studied various idiotisms across different languages.
• The expression 'break a leg' is an English idiotism meaning 'good luck.'
• Understanding idiotisms is essential for mastering a foreign language.
• That old text used the word 'idiotism' to describe what we now call an idiom.