"a rough, quarrelsome person," 1808, originally "lawless backwoodsman," "Of American, but otherwise quite obscure, origin" [OED]. Perhaps from row (n.2) "noisy commotion" (itself of uncertain origin). The adjective, "having the manners of or conducting oneself like a rowdy, rough and noisy," is attested by 1819. Related: Rowdily; rowdiness; rowdyism.
1590s, "frenzy, great excitement," from rave (v.). Meaning "temporary popular enthusiasm" is from 1902; that of "highly flattering review" is by 1926 (when it was noted as a Variety magazine word). By 1960 as "rowdy party;" rave-up was British slang for "wild party" from 1940; the specific sense of "mass party with loud, fast electronic music and often psychedelic drugs" is by 1989.
c. 1200, "broken ground, a rough surface," from rough (adj.). From 1640s as "the disagreeable side of anything." The meaning "a rowdy" is attested by 1837, but Century Dictionary calls this perhaps rather an abbreviation of ruffian conformed in spelling to rough. The specific sense in golf, in reference to the ground at the edge of the greens, is by 1901.
Phrase in the rough "in an unfinished or unprocessed condition" (of timber, etc.) is from 1620s, in rough diamond "diamond in its natural state," which was used figuratively, of persons, by 1700, hence diamond in the rough (by 1874 of persons, in the figurative sense "one whose good character is somewhat masked by rough manners and want of education or style").
popularized 1871, American English, (identified throughout the 1870s as "a California word") "young street rowdy, loafer," especially one involved in violence against Chinese immigrants, "young criminal, gangster;" it appears to have been in use locally from a slightly earlier date and may have begun as a specific name of a gang:
The police have recently been investigating the proceedings of a gang of thieving boys who denominate themselves and are known to the world as the Hoodlum Gang. [San Francisco Golden Era newspaper, Feb. 16, 1868, p.4]
Of unknown origin, though newspapers of the day printed myriad fanciful stories concocted to account for it. A guess perhaps better than average is that it is from German dialectal (Bavarian) Huddellump "ragamuffin" [Barnhart].
What the derivation of the word "hoodlum" is we could never satisfactorily ascertain, though several derivations have been proposed; and it would appear that the word has not been very many years in use. But, however obscure the word may be, there is nothing mysterious about the thing; .... [Walter M. Fisher, "The Californians," London, 1876]
"of the nature of blood, pertaining to blood, bleeding, covered in blood," Old English blodig, adjective from blod (see blood). Common Germanic, compare Old Frisian blodich, Old Saxon blôdag, Dutch bloedig, Old High German bluotag, German blutig. From late 14c. as "involving bloodshed;" 1560s as "bloodthirsty, cruel, tainted with blood-crimes."
It has been a British intensive swear word at least since 1676. Weekley relates it to the purely intensive use of the cognate Dutch bloed, German Blut. But perhaps it ultimately is connected with bloods in the slang sense of "rowdy young aristocrats" (see blood (n.)) via expressions such as bloody drunk "as drunk as a blood."
Partridge reports that it was "respectable" before c. 1750, and it was used by Fielding and Swift, but heavily tabooed c. 1750-c. 1920, perhaps from imagined association with menstruation; Johnson calls it "very vulgar," and OED writes of it, "now constantly in the mouths of the lowest classes, but by respectable people considered 'a horrid word', on par with obscene or profane language."
The onset of the taboo against bloody coincides with the increase in linguistic prudery that presaged the Victorian Era but it is hard to say what the precise cause was in the case of this specific word. Attempts have been made to explain the term's extraordinary shock power by invoking etymology. Theories that derive it from such oaths as "By our Lady" or "God's blood" seem farfetched, however. More likely, the taboo stemmed from the fear that many people have of blood and, in the minds of some, from an association with menstrual bleeding. Whatever, the term was debarred from polite society during the whole of the nineteenth century. [Rawson]
Shaw shocked theatergoers when he put it in the mouth of Eliza Doolittle in "Pygmalion" (1913), and for a time the word was known euphemistically as "the Shavian adjective." It was avoided in print as late as 1936. Bloody Sunday, Jan. 30, 1972, was when 13 civilians were killed by British troops at protest in Londonderry, Northern Ireland.