steeryoudaoicibaDictYouDict[steer 词源字典]
steer: Steer ‘control direction’ [OE] and steer ‘young ox’ [OE] are quite unrelated. The latter comes from a prehistoric Germanic *(s)teuraz, which also produced German and Dutch stier, Swedish tjur, and Danish tyr ‘bull’. It was descended from a base denoting ‘strength’ or ‘sturdiness’ (source also of Sanskrit somethingūra- ‘strong, thick’), and may be related to Latin taurus ‘bull’. Steer ‘control direction’ comes from a prehistoric Germanic *steurjan, source also of German steuern, Dutch stieren, Swedish styra, and Danish styre.

This in turn was derived from the noun *steurō ‘steering’, which also lies behind English stern and the first syllable of starboard.
=> starboard, stern[steer etymology, steer origin, 英语词源]
steer (v.)youdaoicibaDictYouDict
"guide the course of a vehicle," originally by a rudder or something like it, Old English steran (Mercian), stieran (West Saxon) "steer, guide, direct; govern, rule; restrain, correct, punish," from Proto-Germanic *steurjan (cognates: Old Norse styra, Old Frisian stiora, Dutch sturen, Old High German stiuren, German steuern "to steer," Gothic stiurjan "to establish, assert"), related to *steuro "a rudder, a steering," from PIE *steu-ro- (cognates: Greek stauros "stake, pole"), extended form of root *sta- "to stand" (see stet).

The notion is of a stiff, upright pillar or post used in steering, or else perhaps "establish," hence "direct, steer." Intransitive sense also was in Old English. To steer clear of in the figurative sense of "to avoid completely" is recorded from 1723. Related: Steered; steering.
steer (n.)youdaoicibaDictYouDict
"young ox," Old English steor "bullock," from Proto-Germanic *steuraz (cognates: Old Saxon stior, Old Norse stjorr, Swedish tjur, Danish tyr, Middle Dutch, Dutch, German stier, Gothic stiur "bull"), perhaps from PIE *steu-ro-, denoting "larger domestic animal" (see taurus). In U.S. of male beef cattle of any age.