any of various anthozoan coelenterates, esp of the order Actiniaria, having a polypoid body with oral rings of tentacles
See also actinia
sea anemone in American English
any of an order (Actiniaria) of flowerlike, anthozoan sea polyps having a firm, gelatinous, often large, body without a skeleton, topped with petal-like tentacles: they are often brightly colored and live attached to rocks, pilings, etc.