As adjectives the difference between hardy and overhardy

is that hardy is having rugged physical strength; inured to fatigue or hardships. A hardy plant is one that can withstand the extremes of climate, such as frost while overhardy is too hardy; overbold.

As a noun hardy

is a blacksmith's fuller or chisel, having a square shank for insertion into a square hole in an anvil, called the {{term|hardy hole}}.

As a proper noun Hardy

is {{surname|common|from=nicknames}}, originally a nickname for a hardy person.