Is it farther or further?
late Old English sceoh "timid, easily startled," from Proto-Germanic *skeukh(w)az "afraid" (cf. Middle Low German schüwe, Dutch schuw, German scheu "shy;" Old High German sciuhen, German scheuchen "to scare away"). Uncertain cognates outside Germanic, unless in Old Church Slavonic shchuti "to hunt, incite." Italian schivare "to avoid," Old French eschiver "to shun" are Germanic loan-words. Meaning "lacking, short of" is from 1895, American English gambling slang. Related: Shyly; shyness.
"to throw (a missile) with a jerk or toss," 1787, colloquial, of unknown origin and uncertain connection to shy (adj.). Related: Shied; shying.
"to recoil," 1640s, from shy (adj.). Related: Shied; shying.