Origin of Debit and Credit
The term debit comes from Middle French debet from Latin debitum "that which is owed" (the neuter past participle of debere "to owe"). Debit is abbreviated to Di (for debtor).
The term credit comes from the Latin creditum meaning "that which is entrusted or loaned" from the past participle of credere "to trust or entrust". Credit is abbreviated to Ck (for creditor).