partially (adv.)

late 14c., "not whole or total, incomplete;" early 15c., "one-sided, biased, inclined to favor one party in a cause or one side of a question more than the other," also "pertaining to a selfish interest rather than to a common or larger good," from Old French parcial (14c., Modern French partial) and directly from Medieval Latin partialis "divisible, solitary, partial," from Latin pars (genitive partis) "a part, piece, a share, a division" (from PIE root *pere- (2) "to grant, allot").

Weakened sense of "favorably disposed" is from 1580s. Meaning "affecting a part only, not universal or general" is by 1640s.

common adverbial suffix, forming, from adjectives, adverbs signifying "in a manner denoted by" the adjective; Middle English -li, from Old English -lice, from Proto-Germanic *-liko- (source also of Old Frisian -like, Old Saxon -liko, Dutch -lijk, Old High German -licho, German -lich, Old Norse -liga, Gothic -leiko). See -ly (1). It is 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.