omen

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A phenomenon supposed to portend good or evil; a prophetic sign.
2. n. Prognostication; portent: birds of ill omen.
3. v. To be a prophetic sign of; portend.

Century Dictionary and Cyclopedia

1. n. A casual event or occurrence supposed to portend good or evil; a sign or indication of some future event; a prognostic; an augury; a presage. See augur.
2. n. Synonyms Omen, Portent, Sign, Presage, Prognostic, Augury, Foreboding. Omen and portent are the most weighty and supernatural of these words. Omen and sign are likely to refer to that which is more immediate, the others to the more remote. Omen and portent are external: presage and foreboding are internal and subjective; the others are either internal or external. Sign is the most general. Prognostic applies to the prophesying of states of health or kinds of weather, and is the only one of these words that implies a deduction of effect from the collation of causes. Presage and augury are generally favorable, portent and foreboding always unfavorable, the rest either favorable or unfavorable. Omen and augury are most suggestive of the ancient, practice of consulting the gods through priests or augurs. A foreboding may be mistaken; the others are presumably correct. All these words have considerable freedom in figurative use. See foretell, v. t.
3. To prognosticate as an omen; give indication of the future; augur; betoken.
4. To foresee or foretell, as by the aid of an omen; divine; predict.

Wiktionary

1. n. Something which portends or is perceived to portend a good or evil event or circumstance in the future; an augury or foreboding.
2. n. prophetic significance
3. v. To be an omen of.
4. v. To divine or predict from omens.

GNU Webster's 1913

1. n. An occurrence supposed to portend, or show the character of, some future event; any indication or action regarded as a foreshowing; a foreboding; a presage; an augury.
2. v. To divine or to foreshow by signs or portents; to have omens or premonitions regarding; to predict; to augur.

WordNet 3.0

1. n. a sign of something about to happen
2. v. indicate by signs