1. An interval of time characterized by the occurrence of a certain condition, event, or phenomenon: a period of economic prosperity.
2. An interval of time characterized by the prevalence of a specified culture, ideology, or technology: artifacts of the pre-Columbian period.
3. An interval regarded as a distinct evolutionary or developmental phase: Picassos early career is divided into his blue period and rose period.
4. Geology A unit of time, longer than an epoch and shorter than an era.
5. Any of various arbitrary units of time, especially:
a. Any of the divisions of the academic day.
b. Sports & Games A division of the playing time of a game.
6. Physics & Astronomy The time interval between two successive occurrences of a recurrent event or phases of an event; a cycle: the period of a satellites orbit.
7. An instance or occurrence of menstruation.
8. A point or portion of time at which something is ended; a completion or conclusion.
9. The full pause at the end of a spoken sentence.
10. A punctuation mark ( . ) indicating a full stop, placed at the end of declarative sentences and other statements thought to be complete, and after many abbreviations.
11. A sentence of several carefully balanced clauses in formal writing.
a. A metrical unit of quantitative verse consisting of two or more cola.
b. An analogous unit or division of classical Greek or Latin prose.
13. Music A group of two or more phrases within a composition, often made up of 8 or 16 measures and terminating with a cadence.
a. The least interval in the range of the independent variable of a periodic function of a real variable in which all possible values of the dependent variable are assumed.
b. A group of digits separated by commas in a written number.
c. The number of digits that repeat in a repeating decimal. For example, 1/7 = 0.142857142857 . . . has a six-digit period.
15. Chemistry A sequence of elements arranged in order of increasing atomic number and forming one of the horizontal rows in the periodic table.
Of, belonging to, or representing a certain historical age or time: a period piece; period furniture.
Used to emphasize finality, as when expressing a decision or an opinion: Youre not going to the movies tonight, period!
[Middle English periode, from Old French, from Medieval Latin periodus, from Latin perihodos, rhetorical period, from Greek periodos, circuit : peri-, peri- + hodos, way.]
Synonyms: period, epoch, era, age, term These nouns refer to a portion or length of time. Period is the most general: a short waiting period; a difficult period of my life; the Romantic period in music. Epoch refers to a period regarded as being remarkable or memorable: We enter on an epoch of constitutional retrogression (John R. Green). An era is a period of time notable because of new or different aspects or events: How many a man has dated a new era in his life from the reading of a book (Henry David Thoreau). An age is usually a period marked by a distinctive characteristic: the age of Newton; the Iron Age. A term is a period of time to which limits have been set: Senators are elected for a term of six years.
Word History: Many may have wondered why the word period has the sense punctuation mark ( . ) as well as several senses having to do with time. The answer to this question lies in one of the senses of the Greek word periodos from which our word is descended. Periodos, made up of peri-, around, and hodos, way, in addition to meaning such things as going around, way around, going around in a circle, circuit, and with regard to time, cycle or period of time, referred in rhetoric to a group of words organically related in grammar and sense. The Greek word was adopted into Latin as perihodos, which in the Medieval Latin period acquired a new sense related to its use in rhetoric, a punctuation mark used at the end of a rhetorical period. This sense is not recorded in English until 1609, but the word had already entered English as a borrowing from Old French in the sense a cycle of recurrence of a disease, first being recorded in a work written around 1425.
1. a portion of time of indefinable length he spent a period away from home
a. a portion of time specified in some way the Arthurian periodPicassos blue period
b. (as modifier) period costume
3. (Life Sciences & Allied Applications / Physiology) a nontechnical name for an occurrence of menstruation
4. (Earth Sciences / Geological Science) Geology a unit of geological time during which a system of rocks is formed the Jurassic period
5. (Social Science / Education) a division of time, esp of the academic day
6. (Physics / General Physics) PhysicsMaths
a. the time taken to complete one cycle of a regularly recurring phenomenon; the reciprocal of frequency. Symbol T
b. an interval in which the values of a periodic function follow a certain pattern that is duplicated over successive intervals sin x = sin (x + 2π), where 2π is the period
7. (Astronomy) Astronomy
a. the time required by a body to make one complete rotation on its axis
b. the time interval between two successive maxima or minima of light variation of a variable star
8. (Chemistry) Chem one of the horizontal rows of elements in the periodic table. Each period starts with an alkali metal and ends with a rare gas Compare group 
9. (Communication Arts / Printing, Lithography & Bookbinding) another term (esp US and Canadian) for full stop
10. (Literary & Literary Critical Terms) a complete sentence, esp a complex one with several clauses
11. (Music, other) Music a passage or division of a piece of music, usually consisting of two or more contrasting or complementary musical phrases and ending on a cadence Also called sentence
12. (Literature / Poetry) (in classical prosody) a unit consisting of two or more cola
13.Rare a completion or end
[C14 peryod, from Latin periodus, from Greek periodos circuit, from peri- + hodos way]
1. A division of geologic time that is longer than an epoch and shorter than an era.
2. The duration of one cycle of a regularly recurring action or event. See also cyclefrequency
3. An occurrence of menstruation.
4. In the Periodic Table, any of the seven horizontal rows that contain elements arranged in order of increasing atomic number. All the elements in a particular period have the same number of electron shells in their atoms, equal to the number of the period. Thus, atoms of nickel, copper, and zinc, in period four, each have four electron shells. See Periodic Table.
period /prid/ n.1 any segment of time, long or short, that forms part of a longer segment and is notable for particular qualities or characteristics: the dangerous period of an illness||a rainy period in spring||a happy period in my life2 a very long segment of time in the history of the earth: The Jurassic period lasted for millions of years.3 a segment of time in the history of a persons life, a country, etc.: the revolutionary period in American history4 a regular division of time in a school day or a game: the lunch period||The team scored in the second period.5 a womans monthly menstruation: She occasionally has cramps when she gets her period.6 a punctuation mark of a dot ending a sentence: This sentence ends with a period.7period piece: a costume or work of art representative of the style of a particular historical time: That old movie is a period piece, set in medieval France.
Thesaurus: period1 a time, point, episode 2and3 an era, epoch, span of time 4 a session.