Fluidity/fluˈɪdəti/ Definition 1 of 5Pro Tip 1/2Emphasize Ease Use 'fluidity' to stress how easily something moves or flows without interruptions. Oil paints offer the fluidity to blend colors seamlessly. Pro Tip 2/2Physical Properties In science, 'fluidity' refers to a physical property, like how a liquid or gas moves. The fluidity of mercury makes it useful in thermometers.