/stum/ , n. , v. , stummed, stumming .
n.
1. unfermented or partly fermented grape juice.
2. wine in which increased fermentation has taken place because of the addition of stum.
v.t.
3. to increase the fermentation of (wine) by adding stum.
[ 1650-60; stom dumb, dull; cf. F vin muet, G stummer Wein, in the same sense ]