When something becomes void, it means that it has lost its validity or legal force. There are several synonyms that can be used instead of "became void" to communicate the same meaning. One such synonym is "nullified," which refers to the same situation where something is made invalid or has no effect. Another word that can be used is "invalidated," which means that something has been declared not legally valid. Additionally, "canceled" can be used to describe something that has been made void, canceled or annulled. Lastly, "voided," which shares the same root word, can be a suitable synonym for when something becomes void.