roughen (v.)

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."

word-forming element making verbs (such as darken, weaken) from adjectives or nouns, from Old English -nian, from Proto-Germanic *-inojan (also source of Old Norse -na), from PIE adjectival suffix *-no-. Most active in Middle English and early modern English, hence most verbs in -en are comparatively recent.