D defs.my
Entry 1 sense Webster, 1913

Nullify

/nŭl'-əf-īˌ/ · Nul·li·fy · IPA /ˈnʌlɪfaɪ/
01 v. t. To make void; to render invalid; to deprive of legal force or efficacy.
imp. & p. p. Nullified; p. pr. & vb. n. Nullifying
  1. 1.
    To make void; to render invalid; to deprive of legal force or efficacy.
    “Such correspondence would at once nullify the conditions of the probationary system.” I. Taylor.