Definition of quietize in US English:

quietize

(also quietise)

verb

rare
  • with object To make quiet or less noisy; to bring (a person or animal) into a quiet or calm state.

Origin

Late 18th century; earliest use found in Fanny Burney (1752–1840), writer. From quiet + -ize.

Pronunciation

quietize

/ˈkwʌɪətʌɪz/