What is the term for a journal that serves as a book of original entry?

The term for a journal that serves as a book of original entry is "journal." In accounting, a journal is where transactions are first recorded before they are transferred to a ledger. This initial recording is critical because it captures the details of each transaction, including dates, amounts, and descriptions, in chronological order, respecting the principle of double-entry bookkeeping. The journal acts as the first source of recording financial data, ensuring that all transactions are documented systematically.

While other terms like "ledger," "register," and "account book" pertain to the recording of financial information, they serve different purposes. A ledger is used for the classification and summarization of transactions after they have been journaled. A register often refers to a specific type of account—like cash or check registers—that is more specialized. An account book generally refers to any book used to record financial transactions and may include ledgers or journals, but it does not specifically indicate the function of original entry that a journal provides.