Noun

(en noun)

(historical) A member of a Muslim militant group responsible for murdering Christian leaders during the Crusades.

*, II.29:

The Assassines , a nation depending of Phœnicia, are esteemed among the Mahometists of a soveraigne devotion and puritie of maners; they hold, that the readiest and shortest way to gaine Paradise, is to kill some one of a contrary religion.

Someone who intentionally kills a person, especially a professional who kills a public or political figure.

* {{quote-magazine, date=2013-06-29, volume=407, issue=8842, page=55, magazine=(The Economist)

, title= Travels and travails , passage=Even without hovering drones, a lurking assassin , a thumping score and a denouement, the real-life story of Edward Snowden, a rogue spy on the run, could be straight out of the cinema. But, as with Hollywood, the subplots and exotic locations may distract from the real message: America’s discomfort and its foes’ glee.}}

Any ruthless killer.

Noun

(en noun)

That which kills.

There’s a killer on the loose.

''My cat is a habitual bird killer .

Carbon monoxide is a silent killer .

(figuratively) 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 .

(figuratively) Something that is so far ahead of its competition that it effectively kills off that competition.

Various means had were used to steer aircraft in the early years but ailerons were the killer .

(sports) A knockout form of darts or pool involving several players.

A diacritic mark used in Indic scripts to suppress an inherent vowel (e.g., the Hindi viram, the Bengali or Oriya hasanta) or render the entire syllable silent (e.g., the Burmese virama, the Khmer toandakhiat).

So, for example, an invisible ?thaq “killer ” (virama) (U+1039) is not inserted between initial and medial consonants. — http://mercury.soas.ac.uk/wadict/burmese/SOASMyanmar_keyboard_and_font_user_manual.pdf

We have previously shown that there is no “virama” sign as a general “killer ” in Khmer script, unlike, for example, in Devanagari script. — http://std.dkuug.dk/jtc1/sc2/wg2/docs/n2458.pdf

The virama U+1039 MYANMAR SIGN VIRAMA also participates in some common constructions where it appears as a visible sign, commonly termed killer . — http://www.myanmarnlp.net.mm/doc/20010714_implementation_draungmaw1.PPT

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.” — http://unicode.org/reports/tr1.html

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’. — http://www.w3.org/2002/Talks/09-ri-indic/indic-paper.html

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'' — ''Thai: An Essential Grammar By David Smyth

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.'' — ''Thai: An Essential Grammar By David Smyth