killer

Etymology

From Middle English killer, kyller; equivalent to kill + -er.

noun

1. One who or that which kills.
   There’s a killer on the loose.
   My cat is a habitual bird killer.
   Carbon monoxide is a silent killer.
2. (figurative) That which causes stress or is extremely difficult, especially that which may cause failure at a task.
   That test was a killer.
   The final hill in the race course was a killer.
3. (figurative) Something that is so far ahead of its competition that it effectively kills off that competition.
   Digital streaming platforms are CD killers.
4. (figurative) A remarkably impressive person or thing.
   Picture perfect, you don't need no filter / Gorgeous, make 'em drop dead, you're a killer 2020, “Intentions”, in Changes, performed by Justin Bieber ft. Quavo
5. (sports, uncountable) A knockout form of darts or pool involving several players.
6. Ellipsis of killer whale.
   There is, however, one species of whale that habitually preys upon other warm-blooded animals—the killer whale. Really a large dolphin, the killer was classified by Linnaeus as Orcinus orca, and by Cope as Grampus rectipinna. 1966, Sarah Regal Riedman, Elton T. Gustafson, Home is the Sea: for Whales, page 116
7. A club used for killing fish.
8. (philately) A particularly heavy type of handstamp, or portion of one, often obscuring a large part of the postage stamp.
9. Synonym of virama (“kind of diacritical mark”)
   In the course of its adaptation to non-Indo-Aryan languages, the Burmese script has acquired some features that distinguish it from other Indic scripts. The killer, or virama, participates in some common constructions that would be clumsy to handle the way they would be in the other Indic scripts, so the control function of the virama is separated from the diacritic function of the killer. The virama, 0F4D is used to form conjunct consonants, while the killer, 0F52, is a simple diacritic and has no effect on character shaping. The killer is also combined with the VOWEL SIGN O (0F4B) to form the low level tone vowel “o.” When used this way, this symbol is known as hyei hto, or “thrust forward.” 1992, Andy Daniels, Joe Becker, “Unicode Technical Report #1 - Burmese, Khmer, and Ethiopia”, in Unicode Consortium
   For example, although the ‘vowel killer’ diacritic may be called a ‘pulli’ in Tamil, it is still referred to by the Unicode character names as a ‘virama’. 2002, Richard Ishida, “An Introduction to Indic Scripts”, in W3C
   Thai words that have been borrowed from Sanskrit, Pali and English usually try to retain as much of the original spelling as possible; as this will often produce pronunciations that are impossible or misleading, a ‘killer’ symbol is placed above the redundant consonant to indicate that it may be ignored 2002, David Smyth, Thai: An Essential Grammar
   Sometimes the ‘killer’ sign, called kaaran in Thai, cancels out not only the consonant above which it appears, but also the one immediately preceding it. 2002, David Smyth, Thai: An Essential Grammar

adj

1. (slang) Excellent, very good, cool.
   killer feature
   killer view
   It all says that Elephant's Memory is a killer band. 1985, Dave Marsh, Fortunate Son: Criticism and Journalism by America's Best-known Rock Writer, Random House, page 224
   This is followed by a recipe for that very killer dish: "Eat and remember this, the greediest of all Popes" is their merry exhortation. 2000, Various authors, The tablet, page 798
   “Ahhh, Avery,” shouted the Yurtmeister after a full hour of intense volleyball. “That last serve was absolutely killer.” 2009, Amy Bryant, The Great Scavenger Hunt, page 122
   However, there is something very killer about drinking whatever battery acid and paint thinner concoction it is that they make malt liquor out of, in broad daylight, slumped down on the pavement 2010, Al Burian, Burn Collector: Collected Stories from One Through Nine
   That girl was dynamite. Dark hair with killer blue eyes, bronze skin, and an exquisite full-figured body. 2016, Kit Moulton, Annabella, page 108
2. Causing death, destruction, or obliteration.
   killer bee
   killer robot
3. Distressing, uncomfortable.
   I had a killer headache this morning.