1. A tank or other container for keeping and displaying aquatic animals and plants. This is the most common meaning.
* Example: "We visited the aquarium and saw amazing sea creatures like sharks and jellyfish."
2. A building or area housing tanks and displays of aquatic life for public viewing.
* Example: "The San Diego Aquarium is a popular attraction with its diverse collection of marine animals."
The word "aquarium" comes from the Latin word "aquarius", meaning "water carrier". It's a fitting name for a place that houses and displays aquatic life.