Dictionary.com
definitions

ominous

[om-uh-nuh s]
adjective
  1. portending evil or harm; foreboding; threatening; inauspicious: an ominous bank of dark clouds.
  2. indicating the nature of a future event, for good or evil; having the significance of an omen; being a portent: Some of these events were immediately ominous, while others only later revealed themselves as such.

Origin of ominous

1580–90; < Latin ōminōsus portentous, equivalent to ōmin- (stem of ōmen) omen + -ōsus -ous
Related formsom·i·nous·ly, adverbom·i·nous·ness, nounun·om·i·nous, adjectiveun·om·i·nous·ly, adverbun·om·i·nous·ness, noun

Synonyms for ominous

Ominous, portentous, threatening, menacing, fateful are adjectives describing that which forebodes a serious, significant, and often harmful outcome. Ominous, derived from omen “a predictor of outcomes,” usually suggests evil or damaging eventualities: ominous storm clouds; an ominous silence. Portentous, although it may suggest evil results, often stresses a momentous or very important outcome: a portentous moment in history; a portentous escalation of hostilities. Threatening may suggest calamity or great harm but sometimes mere unpleasantness: a threatening rumble from the volcano; A threatening look from his brother caused him to quickly change the subject. Menacing always suggests serious damage as an outcome: a disease menacing the entire population; He advanced with a menacing swagger. Fateful most often stresses the great or decisive importance of what it describes: a fateful encounter between two future leaders; a fateful day that changed our world.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for ominousness

Historical Examples of ominousness

  • To him, as to his mother, the circumstance had at once conveyed a suggestion of ominousness, a hint of possible evil tidings.

  • That face once seen could never be forgotten, and he was overcome by the ominousness of the meeting.

    The False Chevalier

    William Douw Lighthall

  • Too ominous, Mr. Moore thought: let ominousness be kept for one's attitude towards crime.

    East Angels

    Constance Fenimore Woolson

  • Despite the ominousness of the times, Mercer continued with the daily routine, the minutiae of which filled his journal.

British Dictionary definitions for ominousness

ominous

adjective
  1. foreboding evil
  2. serving as or having significance as an omen
Derived Formsominously, adverbominousness, noun

Word Origin for ominous

C16: from Latin ōminōsus, from omen
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
Word Origin and History for ominousness

ominous

adj.

1580s, from Latin ominosus "full of foreboding," from omen (genitive ominis) "foreboding" (see omen). Related: Ominousness.

Online Etymology Dictionary, © 2010 Douglas Harper