stum
/stʌm
/noun [mass noun]
Unfermented grape juice.
verb (stums, stumming, stummed) [with object]
1Prevent or stop the fermentation of (wine) by fumigating a cask with burning sulphur.
2Renew the fermentation of (wine) by adding stum.
Origin
Mid 17th century: from Dutch stom (noun), stommen (verb), from stom 'dumb'.