The definition of the "Goldilocks zone" or "Habitable Zone" from Wikipedia [See Link] is "a region of space where stellar conditions are favorable for life as it is found on Earth".
The habitable zone is not to be confused with the planetary habitability.
The term is derived from the fairy story of Goldilocks and the three bears, where she tries the beds, chairs and porridge and finds only one "Just right".
Some people interpret this as meaning "the only zone (conditions) where life can be found" but this is too limiting. Life forms based on silicon, other chemical reactions etc. may have entirely different Goldilocks Zones
Even on Earth life exists outside of what many users of the term would consider habitable. Animals have been found living in the near boiling waters of hot springs, in deep below freezing waters under the Antarctic ice cap, at the -60oC temperatures of the Antarctic surface, without light in caves, in waters with high concentrations of sulfuric acid, and in the deep sea near "black smokers" or volcanic vents,