money owed or due
the state of owing something, esp money or gratitude
They are heavily in debt
in somebody's debt
owing somebody gratitude; indebted to somebody
Middle English dette, debte from Old French dette something owed, from Latin debitum, past part. of debēre to owe. The b was introduced in the 14th or 15th cent. to conform with Latin debitum, but has never been pronounced: compare doubt1