early 15c., "mythical, legendary," from Latin fabulosus "celebrated in fable;" also "rich in myths," from fabula "story, tale" (see fable (n.)). Meaning "pertaining to fable" is from 1550s. Sense of "incredible" first recorded c. 1600, hence "enormous, immense, amazing," which was trivialized by 1950s to "marvelous, terrific." Slang shortening fab first recorded 1957; popularized in reference to The Beatles, c. 1963.
Fabulous (often contracted to fab(s)) and fantastic are also in that long list of words which boys and girls use for a time to express high commendation and then get tired of, such as, to go no farther back than the present century, topping, spiffing, ripping, wizard, super, posh, smashing. [Gower's 1965 revision of Fowler's "Modern English Usage"]
Related: Fabulously; fabulousness.
"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.