What is Adjusting Entries?

Legal Definition
In accounting/accountancy, adjusting entries are journal entries usually made at the end of an accounting period to allocate income and expenditure to the period in which they actually occurred. The revenue recognition principle is the basis of making adjusting entries that pertain to unearned and accrued revenues under accrual-basis accounting. They are sometimes called Balance Day adjustments because they are made on balance day.

Based on the matching principle of accrual accounting, revenues and associated costs are recognized in the same accounting period. However the actual cash may be received or paid at a different time.
-- Wikipedia
Legal Definition
The final entries posted to a balance sheet that include expenses and revenue incurred that have been adjust to show actual figures that were unable to be calculated prior to the end of a fiscal period.