An omen (also called portent or presage) is a phenomenon that is believed to foretell the future, often signifying the advent of change. People in ancient times believed that omens bring a divine message from their gods.These omens include natural phenomena, for example an eclipse, abnormal births of animals (especially humans) and behaviour of the sacrificial lamb on its way to the slaughter. They had specialists, the diviners, to interpret these omens. They would also use an artificial method, for example, a clay model of a sheep liver, to communicate with their gods in times of crisis. They would expect a binary answer, either yes or no answer, favourable or unfavourable. They did these to predict what would happen in the future and to take action to avoid disaster.Though the word "omen" is usually devoid of reference to the change's nature, hence being possibly either "good" or "bad," the term is more often used in a foreboding sense, as with the word "ominous". The origin of the word is unknown, although it may be connected with the Latin word audire, meaning "to hear."