roughly adv.

Middle English rough (late 14c.), also rouhe, rouwe, roghe, rugh, etc., from Old English ruh, rug- "not smooth to the touch, coarse (of cloth); hairy, shaggy;" of hides, "undressed, untrimmed;" of ground, "uncultivated." This is from West Germanic *rukhwaz "shaggy, hairy, rough" (source also of Middle Dutch ruuch, Dutch ruig, Old High German ruher, German rauh), from Proto-Germanic *rukhaz, which is perhaps related to the source of Sanskrit ruksah "rough;" Latin ruere "to rush, fall violently, collapse," ruina "a collapse;" Lithuanian raukas "wrinkle," rukti "to shrink."

The original -gh- sound was guttural, as in Scottish loch. The form row was a regular variant from early 16c. and lingered in dialects. Of actions, "characterized by harshness or disparity," c. 1300; of land, terrain, late 15c. as "rugged, hard to traverse." Of stormy weather from mid-14c.; by late 14c. of turbulent seas, rude language, discordant sounds.

From mid-14c. as "crudely made;" c. 1600 as "rudely sufficient, not smooth or formed by art." Rough stone "undressed stone mortared together" is from mid-15c. Of writing or literary style, "lacking refinement, unpolished," 1530s. The sense of "approximate" is recorded from c. 1600.

Rough draft (or draught) is from 1690s. Rough-and-ready "rude and disorderly" is by 1832, from an earlier noun (1810), originally military; rough-and-tumble "not elaborately or carefully ordered" is from a style of free-fighting characterized by indiscriminate blows and falls (1810). Rough music "din produced by banging pots, pans, etc. for the purpose of annoying or punishing a neighbor" is by 1708. Rough-snout (c. 1300) was an old term for "a bearded face."

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.