Definition of quieta non movere in US English:

quieta non movere

noun

  • ‘Do not move settled things’; the proverb ‘quieta non movere’ expressing this.

Origin

Mid 18th century; earliest use found in Horace Walpole (1717–1797), author, politician, and patron of the arts. From classical Latin quiēta, use as noun of neuter plural of quiētus quiet + nōn not + movēre move, after the phrase quiēta movēre to disturb settled things (Sallust Catiline 21. 1) See stare decisis.