From Longman Dictionary of Contemporary Englishshushshush /ʃʊʃ/ verb 1 → shush!2 [transitive]QUIET to tell someone to be very quiet, especially by putting your fingers against your lips or by saying ‘shush’ He started to cry and Francesca shushed him.→ See Verb table
Examples from the Corpus
shush• He stood up and shushed the class.shush!shush!spokenQUIET used to tell someone, especially a child, to be quiet SYN shh ‘Shush!’ said Jerry. ‘Not so loud.’ → shushOrigin shush (1900-2000) shh 