back‧date /ˌbækˈdeɪt $ ˈbækdeɪt/ verb [transitive]

1. to make something have its effect from an earlier date
backdate something from/to something
The pay increase will be backdated to January.

2. American English to write an earlier date on a document or cheque than when it was actually written

[TahlilGaran] Dictionary of Contemporary English ▲