The check having a word VOID on it is a voided check. Here the word VOID indicates that the check should not be recognized for the purpose of payment. Though, the check can be left or partially filled up or fully filled up. It can be only used for the bank related information. So you can share account number and bank routing number with the help of void check.
A voided check depicts the check which has been canceled. A check which is void cannot be used.
You can write the word "VOID" in front of the check in large letters. The word void should be written in capital letters and large size covering the entire space in check. But, the numbers at the bottom of your check should not be covered by the VOID term, as these numbers are needed by the recipient of the check in order to establish the link with your bank account.
Be careful while using the word void so that no one can remove or erase it. So in order to void a check, you just need to write a void on the from the side of the check.