"liquor distilled from the juice of sugar cane or molasses," 1650s, apparently a shortening of rumbullion (1651), rombostion (1652), words all of uncertain origin, but suspicion falls on rum (adj.) "excellent, fine, good, valuable;" the phrase rum bouse "good liquor" is attested from 1560s and through 17c. The English word was borrowed into Dutch, German, Swedish, Danish, Spanish, Portuguese, Italian, French, and Russian.
In the Library of Trinity College, Dublin, is a manuscript entitled "A briefe description of the Island of Barbados." It is undated but from internal evidence it must have been written about the year 1651. In describing the various drinks in vogue in Barbados, the writer says : "The chief fudling they make in the Island is Rumbullion alias Kill-Divill, and this is made of sugar canes distilled, a hot, hellish, and terrible liquor. ["The Etymology of the Word Rum," in Timehri, 1885]
Rum was used from c.1800 in North America as a general (hostile) name for intoxicating liquors, hence rum-runner and much other Prohibition-era slang.
Rum I take to be the name which unwashed moralists apply alike to the product distilled from molasses and the noblest juices of the vineyard. Burgundy in "all its sunset glow" is rum. Champagne, soul of "the foaming grape of Eastern France," is rum. ... Sir, I repudiate the loathsome vulgarism as an insult to the first miracle wrought by the Founder of our religion! [Oliver Wendell Holmes, "The Autocrat of the Breakfast-Table," 1871]
"excellent, fine, good, valuable," canting slang, 1560s, also rome, "fine," said to be from Romany rom "male, husband" (see Romany). A very common 16c. cant word (opposed to queer), as in rum kicks "Breeches of gold or silver brocade, or richly laced with gold or silver" [Grose, "Dictionary of the Vulgar Tongue," 1785].
By 1774 it also had come to mean rather the opposite: "odd, strange, bad, queer, spurious," perhaps because it had been so often used approvingly by rogues in reference to one another. Or perhaps this is a different word. This was the main sense after c. 1800.
Rom (or rum) and quier (or queer) enter largely into combination, thus--rom = gallant, fine, clever, excellent, strong; rom-bouse = wine or strong drink; rum-bite = a clever trick or fraud; rum-blowen = a handsome mistress; rum-bung = a full purse; rum-diver = a clever pickpocket; rum-padder = a well-mounted highwayman, etc.: also queere = base, roguish; queer-bung = an empty purse; queer-cole = bad money; queer-diver = a bungling pickpocket; queer-ken = a prison; queer-mort = a foundered whore, and so forth. [John S. Farmer, "Musa Pedestris," 1896]
1778, an arbitrary formation, one of what Farmer describes as "A class of colloquialisms compounded with an intensive prefix" (ram- or rum-), probably suggesting in part rum (adj.) in its old slang sense of "good, fine," and ramp (n.2). In this case apparently suggested by boisterous, robustious, bumptious, etc. Coined about the same time were rumbustical, rambumptious "conceited, self-assertive," rumgumptious "shrewd, bold, rash," rumblegumption, rambuskious "rough," rumstrugenous. Also compare ramshackle, rambunctious.
1540s, "arrange or stow (cargo) in a ship," from the noun rummage "act of arranging cargo in a ship" (1520s), a shortening of French arrumage "arrangement of cargo," from arrumer "to stow goods in the hold of a ship," from a- "to" + -rumer, which is probably from Germanic (compare Old Norse rum "compartment in a ship," Old High German rum "space," Old English rum; see room (n.)). Or else the whole word is from English room (n.) + -age.
The meaning "hunt through or search closely" (the hold of a ship)" is by 1610s; that of "disarrange, disorder, rout out by searching" (reversing the original sense) is from 1590s. Related: Rummaged; rummaging. The noun in the sense of "an act of rummaging, an overhauling search" is by 1753. A rummage sale (1803) originally was a sale at docks of unclaimed goods.
card game, by 1905, rhum, rhummy, a word of unknown origin, perhaps from the drink, by analogy with whisky poker, or from card-playing terms in German (Rum) or Dutch (roem), which are related to German Ruhm "glory, fame." Gin rummy is attested by 1941.
1700, "a distiller" (in colloquial rum-dropper), agent noun from drop (v.). Meaning "small tube from which liquid may be made to fall in drops" is by 1889.