It is used in many words related to water, such as:
* Aquarium: A tank for keeping fish and other aquatic animals.
* Aqueduct: A structure that carries water over a distance.
* Aquatic: Relating to water or living in water.
* Aquamarine: A blue-green gemstone.
* Aqua vitae: A distilled alcoholic beverage, often referred to as "water of life."
Therefore, whenever you see the prefix "aqua", it generally indicates a connection to water.