Aortic insufficiency (AI), also known as aortic regurgitation (AR), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle.
Definition of echidna. : a spiny-coated toothless burrowing nocturnal monotreme mammal (Tachyglossus aculeatus) of Australia, Tasmania, and New Guinea that has a long extensible tongue and long heavy claws and that feeds chiefly on ants; also : a related mammal (Zaglossus bruijni) of New Guinea having a longer snout and shorter spines.
Toxicodendron radicans, commonly known as eastern poison ivy or poison ivy, is a poisonous Asian and North American flowering plant that is well known for causing an itching, irritating, allergic and sometimes painful rash in most people who touch it, caused by urushiol, a clear liquid compound in the plant's sap.