blue-ringed octopus
noun
\ -ˈriŋd-ˈäk-tə-pəs, -ˌpu̇s
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Medical Definition of blue-ringed octopus
: any of several venomous octopuses (genus Hapalochlaena) of the Indo-Pacific region that display brilliant blue rings on the skin when alarmed or agitated and are capable of inflicting a fatal bite due to the injection of tetrodotoxin