Why is the ninth month called September?
zodiac constellation, late Old English, from Latin taurus "bull, bullock, steer," from PIE *tauro- "bull" (cf. Greek tauros, Old Church Slavonic turu "bull, steer;" Lithuanian tauras "aurochs;" Old Prussian tauris "bison"); often said to be from PIE *steu-ro- "be big, be strong, be sturdy" (cf. Sanskrit sthura- "thick, compact," Avestan staora- "big cattle," Middle Persian stor "horse, draft animal," Gothic stiur "young bull," Old English steor, see steer (n.)).
Klein proposes a Semitic origin (cf. Aramaic tora "ox, bull, steer," Hebrew shor, Arabic thor, Ethiopian sor). Meaning "person born under the sign of the bull" is recorded from 1901. Hence also tauromachy "bull-fighting," from Greek tauromakhia (see -machy).
What form great Jove would next devise,
And when his godship would again Taurise?
[William Somerville, 1727]