Entries linking to eerily
also eery, c. 1300, "timid, affected by superstitious fear," north England and Scottish variant of Old English earg "cowardly, fearful, wretched; slow, indolent, useless," from Proto-Germanic *arh- (source also of Old Frisian erg "evil, bad," Middle Dutch arch "bad," Dutch arg, Old High German arg "cowardly, worthless," German arg "bad, wicked," Old Norse argr "unmanly, voluptuous," Swedish arg "malicious"). Sense of "causing fear because of strangeness" is first attested 1792. Finnish arka "cowardly" is a Germanic loan-word.
common adverbial suffix, forming from adjectives adverbs signifying "in a manner denoted by" the adjective, Middle English, from Old English -lice, from Proto-Germanic *-liko- (cognates: Old Frisian -like, Old Saxon -liko, Dutch -lijk, Old High German -licho, German -lich, Old Norse -liga, Gothic -leiko); see -ly (1). Cognate with lich, and identical with like (adj.).
Weekley notes as "curious" that Germanic uses a word essentially meaning "body" for the adverbial formation, while Romanic uses one meaning "mind" (as in French constamment from Latin constanti mente). The modern English form emerged in late Middle English, probably from influence of Old Norse -liga.