Murder
Old English morthor, of Germanic origin; related to Dutch moord and German Mord, from an Indo-European root shared by Sanskrit mará ‘death’ and Latin mors ; reinforced in Middle English by Old French murdre .
wiktionary
From Middle English murder, murdre, mourdre, alteration of earlier murthre(“murder”) (see murther), from Old English morþor(“secret slaying, unlawful killing”) and Old English myrþra(“murder, homicide”), both from Proto-Germanic *murþrą(“death, killing, murder”), from Proto-Indo-European *mr̥tro-(“killing”), from Proto-Indo-European *mer-, *mor-, *mr̥-(“to die”). Akin to Gothic 𐌼𐌰𐌿𐍂𐌸𐍂( maurþr, “murder”), Old High German mord(“murder”), Old Norse morð(“murder”), Old English myrþrian(“to murder”) and morþ.
The -d- in the Middle English form may have been influenced in part by Anglo-Norman murdre, from Old French murdre, from Medieval Latin murdrum (whence the English doublet of murdrum), from Frankish *morþr, *murþr(“murder”), from the same Germanic root, though this may also have been wholly the result of internal development (compare burden, from burthen).
etymonline
murder (n.)
"unlawful killing of another human being by a person of sound mind with premeditated malice," c. 1300, murdre, earlier morþer, from Old English morðor (plural morþras) "secret killing of a person, unlawful killing," also "mortal sin, crime; punishment, torment, misery," from Proto-Germanic *murthran (source also of 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 suffixed form of PIE root *mer- "to rub away, harm" (also "to die" and forming words referring to death and to beings subject to death).
The spelling with -d- probably reflects influence of Anglo-French murdre, from Old French mordre, from Medieval Latin murdrum, which is from the Germanic word. A parallel form murther persisted into 19c.
In Old Norse, custom distinguished morð "secret slaughter" from vig "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. Inverted slang sense of "something excellent or terrific" is by 1940. As the name of a parlor or children's game, by 1933.
murder (v.)
c. 1200 mortheren, "to kill, slay; kill criminally, kill with premeditated malice," from Old English myrðrian, from Proto-Germanic *murthjan (source also of Old High German murdran, German mördren, Gothic maurþjan, from Proto-Germanic *murthra- (see murder (n.)). But OED doubts the Old English verb survived into Middle English and thinks the modern word perhaps from the noun. Forms with -d- begin mid-14c. Meaning "spoil by bad execution" is from 1640s. Related: Murdered; murdering.
