"in a moderate manner or degree," late 14c., from moderate (adj.) + -ly (2).
Entries linking to moderately
moderate adj.
"not excessive in amount, intensity, quality, etc.," late 14c., originally of weather and other physical conditions, from Latin moderatus "within bounds, observing moderation;" figuratively "modest, restrained," past participle of moderari "to regulate, mitigate, restrain, temper, set a measure, keep (something) within measure," from PIE *med-es-, from root *med- "take appropriate measures." The notion is "keeping within due measure." In English, of persons from early 15c., of opinions from 1640s, of prices from 1670s. Related: Moderateness.
-ly 2
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.