a plant that lives in or on water
"The aquatic plants growing at the edge of the pond provided shelter for small fish."
Any aquatic plant.
"The pond was filled with lush green aquatic plants that floated gently on the surface."
operating or living or growing in water
"boats are aquatic vehicles"
"water lilies are aquatic plants"
"fish are aquatic animals"
Relating to water; living in or near water, taking place in water.
"The aquatic plants grew densely along the riverbank, thriving where they could reach sunlight through the shallow water."
In plain English: Aquatic means relating to water, such as fish that live and swim underwater.
"The aquatic animals in this tank require special filters to survive."
Usage: Use aquatic as an adjective before nouns like plants or animals that live entirely underwater, such as aquatic life or aquatic gardens. It specifically describes organisms adapted for a watery environment rather than those that merely visit it temporarily.
The word entered English via Middle French as aquatique, meaning "living in water." It ultimately traces back to the Latin root aqua, which simply means "water."