Skillygalee is a thin, watery gruel made of oatmeal.
Its name, often spelled instead as skilligalee and in other ways, seems to have originally been Irish, though fancifully extended in the early nineteenth century and then abbreviated once more in the 1830s to skilly, a word which was often used as a dismissive term for any insipid beverage.
In 1820 James Hardy Vaux disparaged skillygalee in his Memoirs: “Tolerable flour, of which the cook composed a certain food for breakfast, known among sailors by the name of skilligolee, being in plain English, paste.” (Other writers of that century and the next also compared skillygalee to bill-sticker’s paste, presumably from its consistency rather than taste.) If you were extremely lucky, sugar and butter were added, though common sailors were rarely so fortunate.
Nor were workhouse inmates, for which this was standard fare. Jack London found this out at the start of the twentieth century when he researched his book The People of the Abyss about conditions in London’s East End: “I would be given for supper six ounces of bread and ‘three parts of skilly.’ ‘Three parts’ means three-quarters of a pint, and ‘skilly’ is a fluid concoction of three quarts of oatmeal stirred into three buckets and a half of hot water.”