fluid
adj.
early 15c., "liquid, capable of flowing," from Middle 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.
n.
"substance capable of flowing," 1660s, from fluid, adj.. Related: Fluidal (1869), fluidic (1821, Marmaduke Tulket).
〔蒋〕[flu流，-id形容词后缀，…的] 流动的，流体的，液体的;[转为名词] 流体，液
〔李〕[flu=to flow流；-id a.=having the quality有……性质的→“having the quality of flowing有流动性质的”→]Ⅰa. able to flow流动的