aqua- Also aque- and aqui-.
[Latin aqua, water.]
The usual adjectives are aquatic, relating to an activity that takes place in or on water or to plants or animals that live in water, and aqueous, of or containing water, especially as a solvent or medium.
Aquaculture (sometimes aquiculture) is fish-farming or other water-based cultivation; an aquarium is a tank of water for keeping aquatic animals or plants or a building containing a number of such tanks; an underwater swimmer may use an aqualung in order to breathe; aquarobics are aerobic exercises performed in water; an aquifer is a rock formation containing extractable water. The stone called aquamarine takes its name from Latin aqua marina, seawater, because of its light bluish-green colour. Aqua itself appears in lists of ingredients to indicate the presence of water.
Words that do not belong here include aquiline, having a nose hooked like an eagle's beak (Latin aquila, eagle), and acquaint, acquiesce, and acquit (for which see ad-).