Definition of "nagging"

After breakfast it takes a stout heart and strong nerve to tackle the burden of dishwashing, separator, milk things, disorderly house, interspersed with quarrels, naggings, and interruptions of the children […]

1998, Norah Lillian Lewis, Dear editor and friends, page 127

Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains. Getting rid of these nagging infinities has probably occupied far more effort than was spent in originating the theories.

2012 January, Michael Riordan, “Tackling Infinity”, in American Scientist‎, volume 100, number 1, archived from the original on 30 April 2013, page 86