Debt is when you owe money to someone.
Yes, or it could be a moral debt as well couldn't it?
yes it could, the borrower can be a state, country, government, company or person
Are we talking bonds for stuff like building roads and the like?
yes that is exactly right, the term debt was first used in the 13 century
Wasn't there a law that Christians couldn't loan money back then?
, bonds, notes, and mortgages are all types of debt. The term can also be used metaphorically to cover moral obligations and other interactions not based on economic value. For example, in Western cultures, a person who has been helped by a second person is sometimes said to owe a "debt of gratitude" to the second person.
Etymology.
The English term "debt" was first used in the late 13th century. The term "debt" comes from "dette, from Old French dete,
predetermined answer. Payne notes that the effect of asking a question in different ways or in different contexts can be much larger than the effect of sampling bias, which is the error estimate usually given for a poll. E.g. (from the book) if you ask people "should government go into debt?" the majority will answer "No", but if you ask "Corporations have the right to issue bonds. Should governments also have the right to issue bonds?" the majority will answer "Yes".