guineayoudaoicibaDictYouDict
guinea: [17] Guinea first emerged as the name of a section of the West Africa continent in the late 16th century (its origins are not known, but presumably it was based on an African word). In 1663 the Royal Mint began to produce a gold coin valued at 20 shillings ‘for the use of the Company of Royal Adventurers of England trading with Africa’. It had the figure of an elephant on it.

Straightaway it became known as a guinea, both because its use was connected with the Guinea coast and because it was made from gold obtained there. And what is more, the coins soon came to be much in demand for domestic use: on 29 October 1666 Samuel Pepys recorded ‘And so to my goldsmith to bid him look out for some gold for me; and he tells me that Ginnys, which I bought 2000 of not long ago, and cost me but 18½d. change, will now cost me 22d., and but very few to be had at any price.

However, some more I will have, for they are very convenient – and of easy disposal’. Its value fluctuated, and was not fixed at 21 shillings until 1717. The last one was minted in 1813, but guinea as a term for the amount 21 shillings stayed in use until the early 1970s, when the decimalization of British currency dealt it the deathblow. The guinea pig [17], incidentally, comes from South America, and its name probably arose from a confusion between Guinea and Guiana, on the northern coast of South America.
murder (n.)youdaoicibaDictYouDict
c. 1300, murdre, from Old English morðor (plural morþras) "secret killing of a person, unlawful killing," also "mortal sin, crime; punishment, torment, misery," from Proto-Germanic *murthra- (cognates: Goth maurþr, and, from a variant form of the same root, Old Saxon morth, Old Frisian morth, Old Norse morð, Middle Dutch moort, Dutch moord, German Mord "murder"), from PIE *mrtro-, from root *mer- "to die" (see mortal (adj.)). The spelling with -d- probably reflects influence of Anglo-French murdre, from Old French mordre, from Medieval Latin murdrum, from the Germanic root.

Viking custom, typical of Germanic, distinguished morð (Old Norse) "secret slaughter," from vig (Old Norse) "slaying." The former involved concealment, or slaying a man by night or when asleep, and was a heinous crime. The latter was not a disgrace, if the killer acknowledged his deed, but he was subject to vengeance or demand for compensation.
Mordre wol out that se we day by day. [Chaucer, "Nun's Priest's Tale," c. 1386]
Weakened sense of "very unpleasant situation" is from 1878.