Whisht
Be quiet. As an interjection ('whisht!'), a verb (to silence, or to remain silent), and a noun ('hold your whisht'). Older than 'shush' and quieter in tone. Often used softly to children or to settle a room before someone speaks.
Etymology
Older Scots 'wisht' is attested from 1567; the modern 'whisht' spelling settled by 1718, when Allan Ramsay used it in his Poems. The word is not a borrowing but an interjection that evolved naturally in Scots and northern English speech, parallel to 'hush'. The aspirated initial /ʍ/ is the Scots inheritance; many speakers now pronounce it /wɪʃt/, but the older /ʍɪʃt/ survives in careful Ulster Scots speech. Recorded variants include: wheesht, weesht, wheest, whish, woosht.
In a sentence
Ye need na doubt, I held my whisht - Robert Burns, The Vision, 1786
Whisht, haud your tongue, and sup your sowens. - Walter Scott, Old Mortality, 1816
the place a' wheesht - Robert Louis Stevenson, Catriona, 1893
Historical notes
Whisht has a particular role in Ulster speech and Scots that 'shush' does not match. It can be tender ('whisht now, you're alright'), commanding ('whisht, the news is on'), or quietly social ('haud yer whisht and listen'). The set phrase 'to haud one's wheesht' - to hold one's peace - is documented from Burns in 1786 and is still in everyday Ulster use. Stevenson reached for it in Catriona ('the place a' wheesht') to mark a quiet so complete it counted as an atmosphere.