General English

General Science

  • noun an interval of geological time, the subdivision of an era and itself divided into epochs


  • The time taken for a single cycle of some regular event, such as a complete sequence of the light curve of a variable star, a single journey of an object around its orbit, or between two pulses from a pulsar


  • noun a printing sign (.) used at the end of a piece of text, the full stop


  • An interval of time during which one or more phenomena, conditions, or events occur. For example, a busy period, or an early-failure period.
  • The interval of time that elapses between two consecutive events of a periodically repeated phenomenon. For instance, the duration of a complete cycle. Also, the time interval elapsing between successive occurrences of the same phases of a cyclic event. Its symbol is T.
  • A series of elements which form a horizontal row within a periodic table of chemical elements.
  • symbolT

Information & Library Science

  • interjection used to emphasise that there is no more to be said about a subject
  • noun a particular length of time


  • noun menstruation or the menses, bleeding from the uterus which occurs in a woman each month when the lining of the uterus is shed because no fertilised egg is present

Origin & History of “period”

Period means etymologically ‘going round’. It comes via Old French periode and Latin periodus from Greek períodos, a compound noun formed from the prefix perí- ‘round’ and hódos ‘way’ (source also of English episode, exodus (17th c.), and method). The main sense of the word in modern English, ‘interval of time’ (which first emerged in post-classical Latin), comes from the notion of a ‘repeated cycle of events’ (now more obvious in the derivative periodical (17th c.)).