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/pear"ee euhd/, n.1. a rather large interval of time that is meaningful in the life of a person, in history, etc., because of its particular characteristics: a period of illness; a period of great profitability for a company; a period of social unrest in Germany.2. any specified division or portion of time: poetry of the period from 1603 to 1660.3. a round of time or series of years by which time is measured.4. a round of time marked by the recurrence of some phenomenon or occupied by some recurring process or action.5. the point of completion of a round of time or of the time during which something lasts or happens.6. Educ. a specific length of time during school hours that a student spends in a classroom, laboratory, etc., or has free.7. any of the parts of equal length into which a game is divided.8. the time during which something runs its course.9. the present time.10. the point or character (.) used to mark the end of a declarative sentence, indicate an abbreviation, etc.; full stop.11. a full pause, as is made at the end of a complete sentence; full stop.12. a sentence, esp. a well-balanced, impressive sentence: the stately periods of Churchill.13. a periodic sentence.14. an occurrence of menstruation.15. a time of the month during which menstruation occurs.16. Geol. the basic unit of geologic time, during which a standard rock system is formed: comprising two or more epochs and included with other periods in an era. See table under geologic time.17. Physics. the duration of one complete cycle of a wave or oscillation; the reciprocal of the frequency.18. Music. a division of a composition, usually a passage of eight or sixteen measures, complete or satisfactory in itself, commonly consisting of two or more contrasted or complementary phrases ending with a conclusive cadence.19. Astron.b. Also called period of revolution. the time in which a planet or satellite revolves once about its primary.21. Class. Pros. a group of two or more cola.adj.22. noting, pertaining to, evocative of, imitating, or representing a historical period or the styles current during a specific period of history: period costumes; a period play.23. (used by a speaker or writer to indicate that a decision is irrevocable or that a point is no longer discussable): I forbid you to go, period.[1375-1425; late ME periode ( < MF) < ML periodus, L < Gk períodos circuit, period of time, period in rhetoric, lit., way around. See PERI-, -ODE2]
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IIn geology, the basic unit of the geologic time scale.During these spans of time, specific systems of rocks were formed. Originally, the method for defining the sequence of periods was relative; it was based on stratigraphy and paleontology. Carbon-14 dating and similar methods are now used to determine absolute ages for various periods.II(as used in expressions)Showa periodTaisho period* * *
in geology, the basic unit of the geologic time scale; during these spans of time specific systems of rocks were formed. Originally, the sequential nature of defining periods was a relative one, originating from the superposition of corresponding stratigraphic sequences and the evidence derived from paleontological studies. With the advent of radiometric dating methods, absolute ages for various periods can be determined.▪ musicin music, a unit of melodic organization made up of two balanced phrases in succession; the first phrase, called the antecedent, comes to a point of partial completeness; it is balanced by the consequent, a phrase of the same length that concludes with a sense of greater completeness. The phrase length varies but is typically 2, 4, or 8 measures in moderate tempo; it can be 16 measures in very fast tempos. A double period consists of two periods, with a stronger cadence at the end of the second period; this four-phrase unit often constitutes an entire section.Periodic structure is most apparent in music that exhibits regular phrases, particularly in homophonic song forms and dances. Larger forms with more extensive musical development, such as the sonata and the rondo, often have a structure that is at least partially periodic; periodic structure is less likely to be found in polyphonic (polyphony) textures such as the fugue.Mark DeVoto* * *
Universalium. 2010.