late 14c., "break up military formation;" early 15c. in general sense "throw out of arrangement or into disorder;" see dis- "reverse of" + array (v.) "put in order, arrange." Perhaps formed on the analogy of Old French desareer. Related: Disarrayed.
late 14c., "disorder, confusion, condition of being out of regular order," from dis- "opposite of" + array (n.) "order, arrangement, sequence," or perhaps from Old French desarroi.
word-forming element of Latin origin meaning 1. "lack of, not" (as in dishonest); 2. "opposite of, do the opposite of" (as in disallow); 3. "apart, away" (as in discard), from Old French des- or directly from Latin dis- "apart, asunder, in a different direction, between," figuratively "not, un-," also "exceedingly, utterly." Assimilated as dif- before -f- and to di- before most voiced consonants.
The Latin prefix is from PIE *dis- "apart, asunder" (source also of Old English te-, Old Saxon ti-, Old High German ze-, German zer-). The PIE root is a secondary form of *dwis- and thus is related to Latin bis "twice" (originally *dvis) and to duo, on notion of "two ways, in twain" (hence "apart, asunder").
In classical Latin, dis- paralleled de- and had much the same meaning, but in Late Latin dis- came to be the favored form and this passed into Old French as des-, the form used for compound words formed in Old French, where it increasingly had a privative sense ("not"). In English, many of these words eventually were altered back to dis-, while in French many have been altered back to de-. The usual confusion prevails.
As a living prefix in English, it reverses or negatives what it is affixed to. Sometimes, as in Italian, it is reduced to s- (as in spend, splay, sport, sdain for disdain, and the surnames Spencer and Spence).
mid-14c., "marshal (troops), arrange (an army for battle);" late 14c., "put (things) in order, arrange; get (something) ready, prepare; equip, fit out, put clothing on; adorn, decorate," from Old French areyer, earlier areer "to put in order," from Vulgar Latin *ar-redare "put in order" (source also of Italian arredare), from Latin ad "to" (see ad-) + *redum, from Frankish *ræd- "ready" or some cognate Germanic source, from Proto-Germanic *raidjan "to place in order" (source also of Gothic garadis, Old English geræde "ready;" see ready (adj.)). Related: Arrayed; arraying.
mid-14c., "order or position of things, arrangement, sequence," from Anglo-French arrai, Old French aroi, arroi (12c.), from areer "to put in order" (see array (v.)). From late 14c. as "rank or line of soldiers; troops drawn up in battle formation," also "equipment, furnishings, gear; splendid furnishings, grandeur, magnificence." Meaning "an orderly assemblage" is from 1814.
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<a href="https://www.etymonline.com/word/disarray">Etymology of disarray by etymonline</a>
Harper, D. (n.d.). Etymology of disarray. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/disarray