What is another word for veto?

Here are some words that can be used as synonyms for "veto":

Formal/Official:

* Reject

* Disapprove

* Overrule

* Countermand

* Quash

* Block

* Deny

Informal/Everyday:

* Turn down

* Shoot down

* Nix

* Kill

* Trash

The best synonym will depend on the context and the tone you want to convey.