of drinks, "sweetened and spiced," c. 1600, past-participle adjective from mull (v.2).
Entries linking to mulled
mull v.2
"sweeten, spice, and heat (a drink)," c. 1600, of unknown origin. Perhaps from Dutch mol, a kind of white, sweet beer, or from Flemish molle a kind of beer, and related to words for "to soften." Related: Mulled; mulling.