The Collaborative International Dictionary
Sack posset
Sack \Sack\ (s[a^]k), n. [OE. seck, F. sec dry (cf. Sp. seco,
It. secco), from L. siccus dry, harsh; perhaps akin to Gr.
'ischno`s, Skr. sikata sand, Ir. sesc dry, W. hysp. Cf.
Desiccate.]
A name formerly given to various dry Spanish wines. ``Sherris
sack.''
--Shak.
Sack posset, a posset made of sack, and some other ingredients.