Belly-aching is a term used to describe a continuous complaint or whining about something. When it comes to synonyms, words like whining, moaning, complaining, grumbling, grizzling, and murmuring are commonly used. Each of these words refers to the act of expressing dissatisfaction, either perceived or genuine. The term 'miserable' could also be used as a synonym of 'belly-aching'. Other alternatives include grousing, bleating, and kvetching. All of these words share a similar connotation and imply unnecessary negativity towards something. It is important to remember that although venting is healthy, belly-aching could eventually lead to an overall negative atmosphere.