Definition of Subsidiary ledger:
Special or supporting ledger (such as cost ledger, purchases ledger, sales ledger) that provides more detailed information about individual accounts than a general ledger. Used by firms with larger number of customers (or creditors), these ledgers divide masses of financial data into more manageable parts. Total of all individual accounts in a subsidiary ledger equals the balance of the corresponding summary account (called control account) in the general ledger.
Meaning of Subsidiary ledger & Subsidiary ledger Definition