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English definition of “fluid”

fluid

noun [C/U]    /ˈflu·ɪd/
a substance that flows and is not solid: [U] The doctor drained some fluid from her lungs. medical Fluids are liquids that you drink: [C] Dr. Tay says I need rest and lots of fluids.
(Definition of fluid noun from the Cambridge Academic Content Dictionary © Cambridge University Press)
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