pe·​ri·​od | \ ˈpir-ē-əd \

Definition of period

 (Entry 1 of 2)

1 : the completion of a cycle, a series of events, or a single action : conclusion
2a(1) : an utterance from one full stop to another : sentence
(2) : a well-proportioned sentence of several clauses
b : a musical structure or melodic section usually composed of two or more contrasting or complementary phrases and ending with a cadence
3a : the full pause with which the utterance of a sentence closes
b : end, stop
4 obsolete : goal, purpose
5a(1) : a point . used to mark the end (as of a declarative sentence or an abbreviation)
(2) used interjectionally to emphasize the finality of the preceding statement I don't remember — period
b : a rhythmical unit in Greek verse composed of a series of two or more cola
6a : a portion of time determined by some recurring phenomenon
b(1) : the interval of time required for a cyclic motion or phenomenon to complete a cycle and begin to repeat itself
(2) : a number k that does not change the value of a periodic function f when added to the independent variable especially : the smallest such number
c : a single cyclic occurrence of menstruation
7a : a chronological division : stage
b : a division of geologic time longer than an epoch and included in an era
c : a stage of culture having a definable place in time and space
8a : one of the divisions of the academic day
b : one of the divisions of the playing time of a game



Definition of period (Entry 2 of 2)

: of, relating to, or representing a particular historical period period furniture period costumes

Keep scrolling for more

Synonyms for period

Synonyms: Noun

menstruation, monthlies

Visit the Thesaurus for More 

Choose the Right Synonym for period


period, epoch, era, age mean a division of time. period may designate an extent of time of any length. periods of economic prosperity epoch applies to a period begun or set off by some significant or striking quality, change, or series of events. the steam engine marked a new epoch in industry era suggests a period of history marked by a new or distinct order of things. the era of global communications age is used frequently of a fairly definite period dominated by a prominent figure or feature. the age of Samuel Johnson


period and age mean a portion of time. period can be used of any portion of time, no matter how long or short. We waited a period of five minutes. A new period of space exploration has begun. age is used of a longer period of time that is associated with an important person or outstanding thing. I'm reading about the age of Thomas Jefferson. We live in the computer age.

Examples of period in a Sentence


We have had two power failures in a five-month period. The period between Christmas and New Year's Eve is a very busy one for us. We are studying our country's colonial period. Children go through many changes during the period of adolescence.
See More

First Known Use of period


1532, in the meaning defined at sense 1


1905, in the meaning defined above

History and Etymology for period


Middle English periode, from Middle French, from Medieval Latin, Latin, & Greek; Medieval Latin periodus period of time, punctuation mark, from Latin & Greek; Latin, rhetorical period, from Greek periodos circuit, period of time, rhetorical period, from peri- + hodos way

Keep scrolling for more

Learn More about period

Statistics for period

Look-up Popularity

Time Traveler for period

The first known use of period was in 1532

See more words from the same year

Keep scrolling for more

More Definitions for period



English Language Learners Definition of period

 (Entry 1 of 2)

: a length of time during which a series of events or an action takes place or is completed

: a length of time that is very important in the history of the world, a nation, etc.

: a time that is very important in the life of a person



English Language Learners Definition of period (Entry 2 of 2)

: of, relating to, or typical of a particular time in history


pe·​ri·​od | \ ˈpir-ē-əd \

Kids Definition of period

1 : a punctuation mark . used chiefly to mark the end of a declarative sentence or an abbreviation
2 : a portion of time set apart by some quality a period of cool weather
3 : a portion of time that forms a stage in history the colonial period
4 : one of the divisions of a school day I have math second period.
5 : a single occurrence of menstruation


pe·​ri·​od | \ ˈpir-ē-əd \

Medical Definition of period

1a : a portion of time determined by some recurring phenomenon
b : a single cyclic occurrence of menstruation
2 : a chronological division the period of incubation of a disease

Keep scrolling for more

More from Merriam-Webster on period

Rhyming Dictionary: Words that rhyme with period

Thesaurus: All synonyms and antonyms for period

Spanish Central: Translation of period

Nglish: Translation of period for Spanish Speakers

Britannica English: Translation of period for Arabic Speakers Encyclopedia article about period

Comments on period

What made you want to look up period? Please tell us where you read or heard it (including the quote, if possible).


important, real, or meaningful

Get Word of the Day daily email!

Test Your Vocabulary

Homophone Quiz

  • three-bears-two-of-them-look-like-theyre-whispering-to-a-third-bear-who-looks-chuffed-to-be-the-center-of-attention
  • In order to judge how people felt, the senator's office hired a firm to take a ______.
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!