(~s, negating, ~d)
1.
If one thing ~s another, it causes that other thing to lose the effect or value that it had. (FORMAL)
These weaknesses ~d his otherwise progressive attitude towards the staff.
? confirm
VERB: V n
2.
If someone ~s something, they say that it does not exist. (FORMAL)
He warned that to ~ the results of elections would only make things worse.
? affirm
VERB: V n