What is reverse entry? Please mention examples for reverse entry in accounting terms.

the reverse entry is the opposition of effect of an entry. reverse entry is used in accrual entries and coorections for example

1.
Reverse entry is to nullify the effect of the transaction already recorded. 
2.
Examples may include the reversal of impairment or any provisons recorded

When a mistake or error was committed in an entry,the entry has to be corrected.The entry passed for rectifying the mostake or error is called Reverse entry. It will have anullifying effect of the previous entry. The enry will be in reverse direction of the previous entry.

The reverse entry is used for the correction of an entry.
If you make an entry for sale " Sale debit and Cash credit" you can use reversal entry first " Cash debit and Sale credit " that make entry zero.
Now again " Cash debit & Sale Credit " that makes the entry correct as well as accounts.