outflow noun 6verb 1forms 3 noun6 •The process of flowing out. •Any outward movement. •A fluid that flows out.Borg’s home, which he built with his wife and two sons among tall conifers 33 years ago, overlooks the Nipigon River, an outflow from the lake of the same name. — 2020 •A stream of gaseous material emanating from an active galactic nucleus. •Something that flows out of a sewage treatment plant. •The part of a system that allows material to flow out. verb1 •To flow outward. formsoutflowed · outflowing · outflows