nag 1 (ng)
v. nagged, nag·ging, nags
1. To annoy by constant scolding, complaining, or urging.
2. To torment persistently, as with anxiety or pain.
1. To scold, complain, or find fault constantly: nagging at the children.
2. To be a constant source of anxiety or annoyance: The half-remembered quotation nagged at my mind.
One who nags.
Is calling one a Nag harsh? - Even if 's true. The Nagger may be perfectly justified in their comments or requests. The first time they utter their words surely the Nagee will reasonably comply. The second time, they just want to make sure that Nagee heard them the first time. Third time - well, third time's the charm - or so they've heard. When charm does not seem to be in attendance - the fourth time comes around and still their perfectly reasonable request has gone unaddressed - well, really, what is the Nagee's problem. Why can't Nagee be reasonable, cooperative, compliant, obediant? Oh? Maybe Nagee forgot, maybe or didn't understand, so with great delight, relish, martyrdom, the Nagger utters the words again. And, again. And, again.
Perhaps this 'beating of a dead horse' is the origin of the slang word 'nag' for a played out horse?
Of course, there are those who totally agree with the comment made by Lady Edith Summerskill, British Labour politician, in a speech to Married Women's Association, House of Commons, London, July 14,1960
"Nagging is the repetition of unpalatable truths."
Sometimes, those who are Nagged just don't want to hear " it " - whatever 'it' may be.
Lest you think that nagging is a purely human issue I leave you with this little visual aide -