Which is the closest antonym for the word aver?

Deny, disavow, depending on whether you want to match the brevity or the surface morphology. I thought obver would be good, but it's not in the language -- objure is to take an oath, so it is different. The problem is that avoir, if it truly is the right root of aver, is "to have", and you cannot "un-have" or "dis-have". Thanks to Missi for the answer.