A caudle (or caudel) was a hot drink that recurred in various guises throughout british cuisine from the middle ages into victorian times. it was thick and sweet, and seen as particularly suitable and sustaining for invalids and new mothers. at some periods of history, caudle recipes were based on milk and eggs, like eggnog. later variants were more similar to a gruel, a sort of drinkable oatmeal porridge. like the original forms of posset (a drink of wine and milk, rather than a set dessert), a caudle was usually alcoholic.

Source: Wikipedia