OVER 6個月既支票. 點寫Description 呢?

"Being cheque not presented for payment within 6 months' time now void and reversed."

You can call this a stale cheque.

Technically speaking, the expense had been incurred. So, the entry should be Dr. Bank and Cr. Accounts Payable. Further action should be taken taken whether this expense is no longer a valid item or being cancelled.