whisht

Etymology

From Middle English qwyst, whisht, whist, imitative, though perhaps influenced by other verbs in wh- used in the imperative or by hust (adjective).

intj

1. (Ireland; Britain, especially Scotland, Northumbria) Shush, silence, be quiet!
   “You must have loved him very much,” she said. “Whisht,” said the old woman, “there’s a word that you must never use until there's marrying between you […]” 1952, Neville Shute, chapter 9, in The Far Country, London: Heinemann
2. A sound often used to calm livestock, cattle, sheep etc.