#1 outflow n. [escape, leak, leakage] the discharge of a fluid from some container; "they tried to stop the escape of gas from the damaged pipe"; "he had to clean up the leak". wn #2 outflow n. [effluence, efflux] the process of flowing out. wn #3 outflow n. [spring, fountain, outpouring, natural spring] a natural flow of ground water. wn