Zostera \Zos"te*ra\, n. [NL.] (Bot.) A genus of plants of the Naiadace[ae], or Pondweed family. Zostera marina is commonly known as sea wrack, and eelgrass.
Source: Webster's Revised Unabridged Dictionary (1913)
Eelgrass \Eel"grass`\, n. (Bot.) A plant (Zostera marina), with very long and narrow leaves, growing abundantly in shallow bays along the North Atlantic coast.