Dictionary.com
Thesaurus.com
Synonyms

sinister

American  
[sin-uh-ster] / ˈsɪn ə stər /

adjective

  1. threatening or portending evil, harm, or trouble; ominous.

    a sinister remark.

    Synonyms:
    portentous, inauspicious
    Antonyms:
    benign
  2. bad, evil, base, or wicked; fell.

    his sinister purposes.

  3. unfortunate; disastrous; unfavorable.

    a sinister accident.

    Synonyms:
    unlucky
    Antonyms:
    favorable
  4. of or on the left side; left.

  5. Heraldry. noting the side of an escutcheon or achievement of arms that is to the left of the bearer (dexter ).


sinister British  
/ ˈsɪnɪstə /

adjective

  1. threatening or suggesting evil or harm; ominous

    a sinister glance

  2. evil or treacherous, esp in a mysterious way

  3. (usually postpositive) heraldry of, on, or starting from the left side from the bearer's point of view and therefore on the spectator's right

  4. archaic located on the left side

  5. archaic (of signs, omens, etc) unfavourable

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

  • sinisterly adverb
  • sinisterness noun
  • unsinister adjective
  • unsinisterly adverb
  • unsinisterness noun

Etymology

Origin of sinister

First recorded in 1375–1425; late Middle English, from Latin: “on the left hand or side,” hence, “unfavorable, injurious”

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Horning suspected something more sinister was at play.

From The Wall Street Journal

Miriam is vivacious and energetic but dogged by an unexplained sin from her earlier life—a sin that vests itself in the sinister person of her “model.”

From The Wall Street Journal

He also accused Iran of "pursuing sinister nuclear ambitions", though Tehran has always insisted its programme is for civilian purposes.

From Barron's

The first, which he began making in the early 1960s, were mysterious, sinisterly bejeweled boxes, little containers of compressed surrealism festooned with hundreds of shiny straight pins.

From The Wall Street Journal

Other artists who have helped to shape the somewhat sinister Peaky Blinders sound, including Nick Cave, Lankum and McLusky, will also feature, along with Girl In The Year Above and Chatten, both covering Massive Attack.

From BBC