Ductus is a term that is commonly used in medicine and engineering to refer to a tube or pipe that is used to transport fluids or air. In the medical field, ductus refers to the duct connecting the pulmonary artery to the aorta that allows the blood to bypass the lungs before birth. Synonyms for ductus include tube, channel, conduit, pipe, passage, artery, vein, hose, and canal. In engineering, ductus is found in the form of ventilation ducts or heating ducts. The word ductus is usually used in technical contexts, and there are many other words that can be used to refer to these structures depending on the context.