nullify

vt.使无效，废弃，取消

nuclear energy (also nuclear power), nuclear family, nuclear war, nuclear winter, nuclear-free, nucleate, nucleic acid, nucleolus, nucleus, nude, nudge, nudism, nudist, nudist camp (also nudist colony), nudity, nugatory, nugget, nuisance, null, nullification, nullity, numb, number, number one, numberless, numbly, numbness, numeracy, numeral, numerate, numeration, numerator, numerical, numerically, numerous, numinous, numismatics, numismatist, numskull (also numbskull), nun,