The definition I read is: “Through the mid-19th century, debtors’ prisons (usually similar in form to locked workhouses) were a common way to deal with unpaid debt in Western Europe.[1] Destitute persons who were unable to pay a court-ordered judgment would be incarcerated in these prisons until they had worked off their debt via labour or secured outside funds to pay the balance.” (Wikipedia)

If it was court ordered, would that not be a sentence?