Why is the ninth month called September?
1650s, "whirlpool, eddying mass," from Latin vortex, variant of vertex "an eddy of water, wind, or flame; whirlpool; whirlwind," from stem of vertere "to turn" (see versus). Plural form is vortices. Became prominent in 17c. theories of astrophysics (by Descartes, etc.). In reference to human affairs, it is attested from 1761. Vorticism as a movement in British arts and literature is attested from 1914, coined by Ezra Pound.
vortex vor·tex (vôr'těks')
n. pl. vor·tex·es or vor·ti·ces (-tĭ-sēz')
A spiral motion of fluid within a limited area, especially a whirling mass of water or air that sucks everything near it toward its center.
Plural vortexes or vortices (vôr'tĭ-sēz')
A circular, spiral, or helical motion in a fluid (such as a gas) or the fluid in such a motion. A vortex often forms around areas of low pressure and attracts the fluid (and the objects moving within it) toward its center. Tornados are examples of vortexes; vortexes that form around flying objects are a source of turbulence and drag. See also eddy.