shyness (n.)

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.

word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).