dem·i-glace 
(dĕmē-glăs′)
(dĕmē-glăs′)n.
A rich, reduced brown sauce usually seasoned with wine and used as a base for other sauces.
[French : demi-, demi- (from demi, half, from Old French; see DEMI-) + glace, glaze, heavily reduced sauce (from Old French, ice; see GLACIER).]