ramshackle adj.

mid-13c., ransaken, "to plunder; to make a search, search thoroughly," from a Scandinavian source akin to Old Norse rannsaka "to pillage," literally "search the house" (especially legally, for stolen goods), from rann "house," from Proto-Germanic *raznan (c.f. Gothic razn, Old English ærn "house;" Old English rægn "a plank, ceiling;" see barn) + saka "to search," related to Old Norse soekja "seek" (see seek). Properly it would have evolved as *ransake; the present form perhaps was influenced by sack (v.1). Related: Ransacked; ransacking.

1778, an arbitrary formation, one of what Farmer describes as "A 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.

"very roughly built house or cabin," 1878, American English and Canadian English, originally in reference to temporary dwellings made by homesteaders while securing a claim, a word of unknown origin. Perhaps it is from Mexican Spanish jacal (from Nahuatl (Aztecan) xacalli "wooden hut"). Or perhaps it is a back-formation from dialectal English shackly "shaky, rickety" (1843), a derivative of shack, a dialectal variant of shake (v.). Another theory derives shack from ramshackle.

Yet another derives it from the verb shack meaning "to hibernate," as a bear or other animal, which is also a variant of shake (v.) in the sense of "be shed or fall," used of grain fallen from the ear and available for food for hogs, etc. (1520s); hence "the act or right of sending pigs or poultry out to 'run shack' after a harvest." Also compare shake-down "impromptu bed made upon loose straw" (1730).

The slang meaning "house" is attested by 1910. In early radio enthusiast slang, it was the word for a room or office set aside for wireless use, 1919, perhaps from earlier U.S. Navy use (1917).

The perhaps-related verb in the "hibernate" sense by 1891 in the U.S. West was used in reference to men who "hole up" for the winter; it is attested from 1927 as "to put up for the night;" the phrase shack up "cohabit" is recorded by 1935 (Zora Neale Hurston).