Entries linking to severely
1540s, from French severe (12c., Modern French sévère) or directly from Latin severus "serious, grave, strict, austere," which is probably from PIE root *segh- "to have, hold," on the notion of "steadfastness, toughness." From 1660s with reference to styles or tastes; from 1725 of diseases.
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.
Others are reading
a severely impaired heart
peered severely over her glasses
she was severely affected by the bank's failure