A gear grinder is a term that represents someone who complains about everything. This person can be described using a range of synonyms, such as the following. A whiner is someone who constantly complains about their problems, while a grumbler is a person who is always dissatisfied and complaining. A faultfinder is someone who always seems to find something wrong with everything. A nitpicker is someone who complains about small details, while a sniveler is someone who complains in a whiny or tearful way. Finally, a malcontent is a person who is never satisfied and always complains, regardless of the circumstances.