negate
Concise Oxford English Dictionary © 2008 Oxford University Press:
negate /nɪˈgeɪt/
▶verb
- 1 nullify; make ineffective.
- 2 Logic & Grammar make (a clause, sentence, or proposition) negative in meaning.
- 3 deny the existence of.
– origin C17 (earlier (ME) as negation): from L. negat-, negare ‘deny’.
'negate' also found in these Oxford entries:

