[Cnidaria] Main body of the medusa, generally resembling a bell or an umbrella, excluding manubrium and tentacles. The outer, generally convex, surface of the umbrella is the exumbrellar surface (exumbrella), the inner concave surface is the subumbrellar surface (subumbrella) and the cavity bounded by the subumbrellar surface is the subumbrellar cavity. The edge of the umbrella is the umbrella margin.

Alternative forms for umbrella : bell, umbrellar.