In accounting, dr. is the abbreviation for the word debit. (Today, accountants and bookkeepers use the term debit, but five centuries ago in Italy, the term included the letter "r".)
In accounting and bookkeeping, debit or dr. indicates an entry on the left side of a general ledger account. Typically, the accounts for assets and expenses will have debit balances. Debit entries will also reduce the credit balances typically found in the liability and stockholders' equity accounts.