naysay

/N EY0 S EY1/
noun
  1. 1

    A refusal, denial, or negation.

verb
  1. 1

    To speak negatively of something.

  2. 2

    To reply no.

Source: https://en.wiktionary.org/wiki/nay-say, https://en.wiktionary.org/wiki/naysay