zodiac constellation, late Old English, from Latin taurus "bull, bullock, steer," also the name of the constellation, from PIE *tau-ro- "bull" (source also of Greek tauros, Old Church Slavonic turu "bull, steer;" Lithuanian tauras "aurochs;" Old Prussian tauris "bison"); from PIE *tauro- "bull," from root *(s)taeu- "stout, standing, strong" (source also of Sanskrit sthura- "thick, compact," Avestan staora- "big cattle," Middle Persian stor "horse, draft animal," Gothic stiur "young bull," Old English steor); extended form of root *sta- "to stand, make or be firm."
Klein proposes a Semitic origin (compare Aramaic tora "ox, bull, steer," Hebrew shor, Arabic thor, Ethiopian sor). De Vaan writes: "The earlier history of the word is uncertain: there is no cognate in [Indo-Iranian] or Tocharian, whereas there are Semitic words for 'bull' which are conspicuously similar. Hence, it may have been an early loanword of the form *tauro- into the western IE languages." Meaning "person born under the sign of the bull" is recorded from 1901. The Taurid meteors (peaking Nov. 20) so called from 1878.
At midnight revels when the gossips met,
He was the theme of their eternal chat:
This ask'd what form great Jove would next devise,
And when his godship would again Taurise?
[William Somerville, "The Wife," 1727]