<p><strong>Noun</strong></p><ul><li>a particular period of time marked by distinctive features, events, etc.: The treaty ushered in an epoch of peace and goodwill.</li><li>Synonyms: time, era, date, age</li><li>the beginning of a distinctive period in the history of anything: The splitting of the atom marked an epoch in scientific discovery.</li><li>a point of time distinguished by a particular event or state of affairs; a memorable date: His coming of age was an epoch in his life.</li><li>Geology. any of several divisions of a geologic period during which a geologic series is formed.</li><li>Astronomy. an arbitrarily fixed instant of time or date, usually the beginning of a century or half-century, used as a reference in giving the elements of a planetary orbit or the like.</li><li>the mean longitude of a planet as seen from the sun at such an instant or date.</li><li>Physics. the displacement from zero at zero time of a body undergoing simple harmonic motion.</li></ul>