A verrrry dumb mantra? (or a ‘figure of speech’)

noun

1. An expression in the usage of a language that is peculiar to itself either in having a meaning that cannot be derived from the conjoined meanings of its elements (such as up in the air for “undecided”) or in its grammatically atypical use of words (such as give way)
2. The language peculiar to a people or to a district, community, or class dialect
3. The syntactical, grammatical, or structural form peculiar to a language
4. A style or form of artistic expression that is characteristic of an individual, a period or movement, or a medium or instrument

   "the modern jazz idiom"