6 letters · 8 points in Scrabble
originInherited from Middle English *mystal, from myx (“dung”) + stal (“shed”). For the disappearance of /k/ before /st/, compare the disappearance of /x/ before /st/ in Anglian Old English hēst (“highest”), nēst (“nearest”), and sesta (“sixth”), surviving in Scots neest (“next”).
Etymology from Wiktionary, CC BY-SA 3.0