Omination is a noun that refers to a feeling or expression of gloomy or foreboding signs or events. Synonyms for this word may include "portent," which means a warning or indication of future events, "presage," which refers to a feeling or impression that something bad is about to happen, or "harbinger," which suggests something or someone that signals the approach of something ominous or dangerous. Other synonyms include "omen," "sign," "premonition," and "forewarning." Each of these words conveys subtle differences in meaning but all share the common thread of something ominous or unsettling on the horizon.