delinquent

Short definition from Wiktionary

Adjective

1. 1
   Late or failing to pay a debt or other financial obligation, like a mortgage or loan.
2. 2
   Of a payment or other financial obligation: late or otherwise unfulfilled.
3. 3
   Failing in or neglectful of a duty or obligation; guilty of a misdeed or offense

Noun

1. 1
   One who disobeys or breaks rules or laws, or who acts against another's wishes.
2. 2
   A person who has not paid their debts.
3. 3
   A royalist in the First English Civil War (1642-1646).