obeliaPronunciation: /ə(ʊ)ˈbiːlɪə/Definition of obelia noun Zoology a sedentary colonial coelenterate with upright branching stems bearing minute cups in which the polyps sit. Genus Obelia, class Hydrozoa Origin:modern Latin, from Greek obelos 'pointed pillar'obelia in other Oxford dictionaries Definition of obelia in the US English dictionary