Home›Browse›S›serous fluidserous fluidOur editors are putting together more complete content — check back in about 20 minutesserous fluidserous fluid — nounnoun1. a thin, watery fluid produced by serous membranes in the body1.nounDefinitiona thin, watery fluid produced by serous membranes in the bodyExampleThe serous fluid in the pleural cavity lubricates the lungs.