scantly adv.

mid-14c., "short or insufficient in quantity, rather less than is wanted for the purpose," from a Scandinavian source such as Old Norse skamt, neuter of skammr "short, brief," from Proto-Germanic *skamma- (source also of Old English scamm "short," Old High German skemmen "to shorten"), perhaps ultimately "hornless" (from PIE *kem- (1) "hornless;" see hind (n.)).

Also in Middle English as a noun, "dearth, scant supply, scarcity," from Old Norse.

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.