Hydrostatic equilibrium refers to the balance between the inward force of gravity and the outward pressure of a fluid. There are several synonyms for hydrostatic equilibrium, including hydrostatic balance, hydrostatic stability, and hydrostatic equilibrium state. These terms all describe the same concept and are used interchangeably in various scientific fields such as astronomy, geology, and fluid mechanics. Other related terms that are often used alongside hydrostatic equilibrium are dynamic equilibrium and thermal equilibrium. Understanding the concept of hydrostatic equilibrium is crucial in studying the characteristics of celestial bodies such as stars, planets, and galaxies.