fluid /ˈfluːɪd/noun 3adjective 5forms 3 noun3 •a liquid such as water, oil or blood, and not a gas or a solidThe Doctor: Get a good night's sleep and drink plenty of fluids. / Kes: Fluids? / The Doctor: Everybody should drink plenty of fluids. — 1995 •Any substance which can flow with relative ease, tends to assume the shape of its container, and obeys Bernoulli's principle; a liquid, gas or plasma. •(informal) Intravenous fluids. adjective5 •Of or relating to fluid. •In a state of flux; subject to change. •(rare) Genderfluid.Oh, Loki made sure of that. My mortal parents blamed him for the way I was, for being fluid. — 2017 •Moving smoothly, or giving the impression of a liquid in motion.Tom of the fluid pelvis, undulating about the living room in defiance of Michael's taboo on sensuality. — 1983 •Convertible into cash. formsfluids · more fluid · most fluid