n. 25B6; noun the fluid seeps up the tube : LIQUID, watery substance, solution; GAS, gaseous substance, vapour.
a fluid substance : FREE-FLOWING; liquid, liquefied, melted, molten, runny, running; gaseous, gassy.
his plans were still fluid : ADAPTABLE, flexible, adjustable, open-ended, open, open to change, changeable, variable.
the fluid state of affairs : FLUCTUATING, changeable, subject/likely to change, (ever-)shifting, inconstant; unstable, unsettled, turbulent, volatile, mercurial, protean.
he stood up in one fluid movement : SMOOTH, fluent, flowing, effortless, easy, continuous; graceful, elegant.
solid, firm, static, jerky.