shy adj.

Middle English shei, "easily frightened or startled," from late Old English sceoh "timid, easily startled," from Proto-Germanic *skeukh(w)az "afraid" (source also of Middle Low German schüwe, Dutch schuw, German scheu "shy;" Old High German sciuhen, German scheuchen "to scare away"). Cognates outside Germanic are uncertain, unless perhaps in Old Church Slavonic shchuti "to hunt, incite." Italian schivare "to avoid," Old French eschiver "to shun" are Germanic loan-words.

The meaning "shrinking from contact with others, difficult of approach because of timidity" is by c. 1600. The meaning "lacking, short of" is from 1895, American English gambling slang. As the last element of a compound (gun-shy, etc.) "frightened, averse, reluctant," by 1849.

1787, shie, "throw a missile with a jerk or toss," 1787, chiefly colloquial according to OED, of obscure origin and uncertain connection to shy (adj.). The transitive sense of "fling, throw, toss" (with at) is by 1793. Related: Shied; shying.

"to recoil, take sudden fright or aversion," 1640s, from shy (adj.). The transitive sense of "shun, avoid" (someone or something) is by 1802. To shy away from "find a means of evading" is by 1867. Related: Shied; shying.