c. 1600, from French fluidité, from fluide (see fluid (adj.)), or else formed in English from fluid.
Entries linking to fluidity
fluid adj.
early 15c., "liquid, capable of flowing," from Old French fluide (14c.) and directly from Latin fluidus "fluid, flowing, moist," from fluere "to flow" (see fluent). Figurative use, of non-material things, "not fixed or rigid," from 1640s. Related: Fluidly.