nag in WordNet English dictionary

1. someone (especially a woman) who annoys people by constantly finding fault
   scold  scolder  nag  nagger  common scold 
   
2. an old or over-worked horse
   hack  jade  nag  plug 
   

1. bother persistently with trivial complaints
   "She nags her husband all day long"
   nag  peck  hen-peck 
   
2. remind or urge constantly
   "she nagged to take a vacation"
   nag 
   
3. worry persistently
   "nagging concerns and doubts"
   nag