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English definition of “fluid”

fluid

noun [C or U] uk   /ˈfluː.ɪd/ us  
C2 a substance that flows and is not solid: If you have a fever you should drink plenty of fluid(s). The virus is contracted through exchange of bodily fluids.

fluid

adjective uk   /ˈfluː.ɪd/ us  

fluid adjective (MOVEMENT)

C2 smooth and continuous: fluid movements

fluid adjective (LIKELY TO CHANGE)

If situations, ideas, or plans are fluid, they are not fixed and are likely to change, often repeatedly and unexpectedly: The military situation is still very fluid.
(Definition of fluid from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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