- a flowering plant (Zostera marina) of the pondweed family, that grows underwater and has long, grasslike leaves
- tape grass
- Any of several submersed marine plants of the genus Zostera, having straplike leaves and found along northern and southern temperate coasts worldwide.
- Any of several submersed freshwater plants of the genus Vallisneria, having long flat or twisted leaves and often grown as aquarium plants. Also called tape grass, wild celery.
(countable and uncountable, plural eelgrasses)
- A plant (Zostera marina), with very long and narrow leaves, growing abundantly in shallow bays along the North Atlantic coast.