the.com/fluid dynamics

means The branch of physics that studies how liquids and gases move, flow, and respond to forces like pressure and viscosity.

from From Latin 'fluidus' (flowing), itself from 'fluere' (to flow) — the same root giving us 'fluent' and 'influence.' 'Dynamics' traces to Greek 'dynamis' (power), via 'dynasthai' (to be able, to have strength). The two words were wedded as a formal scientific term around the 19th century, when physicists and engineers needed a name for the mathematics of moving fluids — the behavior of rivers, air, and blood alike — born from the broader study of mechanics splitting into specialized branches as the science matured.