also red, c. 1300, redden, "to clear" (a space, etc.), "rid of encumbrance," from Old English hreddan "to save, free from (Satan, guilt, etc.), deliver, recover, rescue," from Proto-Germanic *hradjan (source also of Old Frisian hredda, Dutch redden, Old High German retten).
Sense evolution tended to merge it with unrelated rid. It is also possibly influenced by Old English rædan "to arrange," which is related to Old English geræde, source of ready (adj.). Related: Redding.
A dialect word in Scotland and northern England, where it has had senses of "to fix" (boundaries), "to comb" (out one's hair), "to separate" (combatants), "to settle" (a quarrel). The exception to the limited use is the meaning "to put in order, to make neat or trim" (1718), especially in redd up, which is in general use in England and the U.S. The same phrase, in the same sense, in Pennsylvania Dutch may be from cognate Low German and Dutch redden, obviously connected historically to the English word, "but the origin and relationship of the forms is not clear" [OED].
early 13c., redien, "to administer" (a sense now obsolete); c. 1300, "to take aim;" mid-14c., "to make (something) ready, prepare, put into proper condition or order," from ready (adj.). "Somewhat rare between the 15th and 19th c." [OED]. Related: Readied; readying. Compare Dutch reeden "prepare, dress; German bereiten, Danish berede "prepare, get ready;" also compare redd (v.).
c. 1200, ridden, "clear (a space); set free, save," from Old English *ryddan (past participle geryd) or else from a Scandinavian source akin to Old Norse ryðja (past tense ruddi, past participle ruddr) "to clear (land) of obstructions," from Proto-Germanic *reudijan (source also of Old High German riuten, German reuten "to clear land," Old Frisian rothia "to clear," Old English -royd "clearing," common in northern place names), from PIE root *reudh- "to clear land."
Meaning "be rid of, be freed from" (something troublesome or useless) is from mid-15c. The general sense of "to make (someone or someplace) free (of someone or something else)" emerged by 16c. The senses have merged somewhat with those in Northern English, Scottish, and U.S. dialectal redd (q.v.). To get rid of (something or someone) is from 1660s. Related: Ridden; ridding.
"waxy, fatty stuff in the head of certain whales," late 15c., from Medieval Latin sperma ceti "sperm of a whale" (it has when fresh something of the appearance of sperm), from Latin sperma "seed, semen" (see sperm) + ceti, genitive of cetus "whale, large sea animal" (see Cetacea). The substance in olden times was credited with medicinal properties, as well as being used for candle oil.
Use ... Sperma Cete ana with redd Wyne when ye wax old. [Sir George Ripley, "The Compound of Alchemy," 1471]
Scientists still are not sure exactly what it does. Sperm whale, short for spermaceti whale, is from 1830.