1. [n]  a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations; "in England they call a period a stop"
2. [n]  the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause; "the women were sickly and subject to excessive menstruation"; "a woman does not take the gout unless her menses be stopped"--Hippocrates; "the semen begins to appear in males and to be emitted at the same time of life that the catamenia begin to flow in females"--Aristotle
3. [n]  
4. [n]  the end or completion of something; "death put a period to his endeavors"; "a change soon put a period to my tranquility"
5. [n]  a unit of geological time during which a system of rocks formed; "ganoid fishes swarmed during the earlier geological periods"
6. [n]  one of three periods of play in hockey games
7. [n]  the interval taken to complete one cycle of a regularly repeating phenomenon
8. [n]  a stage in the history of a culture having a definable place in space and time; "a novel from the Victorian period"

Period.
Discusses the physical and psychological changes at the onset of menstruation. Includes a guide for parents and teachers.

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1. \Pe"ri*od\, n. [L. periodus, Gr. ? a going round, a way
   round, a circumference, a period of time; ? round, about + ?
   a way: cf. F. p['e]riode.]
   1. A portion of time as limited and determined by some
      recurring phenomenon, as by the completion of a revolution
      of one of the heavenly bodies; a division of time, as a
      series of years, months, or days, in which something is
      completed, and ready to recommence and go on in the same
      order; as, the period of the sun, or the earth, or a
      comet.
   2. Hence: A stated and recurring interval of time; more
      generally, an interval of time specified or left
      indefinite; a certain series of years, months, days, or
      the like; a time; a cycle; an age; an epoch; as, the
      period of the Roman republic.
            How by art to make plants more lasting than their
            ordinary period.                      --Bacon.
   3. (Geol.) One of the great divisions of geological time; as,
      the Tertiary period; the Glacial period. See the Chart of
      {Geology}.
   4. The termination or completion of a revolution, cycle,
      series of events, single event, or act; hence, a limit; a
      bound; an end; a conclusion. --Bacon.
            So spake the archangel Michael; then paused, As at
            the world's great period.             --Milton.
            Evils which shall never end till eternity hath a
            period.                               --Jer. Taylor.
            This is the period of my ambition.    --Shak.
   5. (Rhet.) A complete sentence, from one full stop to
      another; esp., a well-proportioned, harmonious sentence.
      ``Devolved his rounded periods.'' --Tennyson.
            Periods are beautiful when they are not too long.
                                                  --B. Johnson.
   Note: The period, according to Heyse, is a compound sentence
         consisting of a protasis and apodosis; according to
         Becker, it is the appropriate form for the
         co["o]rdinate propositions related by antithesis or
         causality. --Gibbs.
   6. (Print.) The punctuation point [.] that marks the end of a
      complete sentence, or of an abbreviated word.
   7. (Math.) One of several similar sets of figures or terms
      usually marked by points or commas placed at regular
      intervals, as in numeration, in the extraction of roots,
      and in circulating decimals.
   8. (Med.) The time of the exacerbation and remission of a
      disease, or of the paroxysm and intermission.
   9. (Mus.) A complete musical sentence.
   {The period}, the present or current time, as distinguished
      from all other times.
   Syn: Time; date; epoch; era; age; duration; limit; bound;
        end; conclusion; determination.
   

2. \Pe"ri*od\, v. t.
   To put an end to. [Obs.] --Shak.
   

3. \Pe"ri*od\, v. i.
   To come to a period; to conclude. [Obs.] ``You may period
   upon this, that,'' etc. --Felthman.