Epoch vs. Period — What's the Difference?

In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.

An interval of time characterized by the occurrence of a certain condition, event, or phenomenon

A particular period of history, especially one considered remarkable or noteworthy.

An interval of time characterized by the prevalence of a specified culture, ideology, or technology

A unit of geologic time that is a division of a period.

An interval regarded as a distinct evolutionary or developmental phase

(Astronomy) An instant in time that is arbitrarily selected as a point of reference for specification of celestial coordinates.

(Geology) A unit of time, longer than an epoch and shorter than an era.

A particular period of history, or of a person's life, especially one considered noteworthy or remarkable.

Any of the divisions of the academic day.

A notable event which marks the beginning of such a period.

Sports & Games A division of the playing time of a game.

A specific instant in time, chosen as the point of reference or zero value of a system that involves identifying instants of time.

Physics & Astronomy The time interval between two successive occurrences of a recurrent event or phases of an event; a cycle

(geology) A geochronologic unit of hundreds of thousands to millions of years; a subdivision of a period, and subdivided into ages (or sometimes subepochs).

See menstrual period.

(ML) One complete presentation of the training data set to an iterative machine learning algorithm.

A point or portion of time at which something is ended; a completion or conclusion.

To divide (data) into segments by time period.

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.

A fixed point of time, established in history by the occurrence of some grand or remarkable event; a point of time marked by an event of great subsequent influence; as, the epoch of the creation; the birth of Christ was the epoch which gave rise to the Christian era.

The full pause at the end of a spoken sentence.

A period of time, longer or shorter, remarkable for events of great subsequent influence; a memorable period; as, the epoch of maritime discovery, or of the Reformation.

A sentence of several carefully balanced clauses in formal writing.

A division of time characterized by the prevalence of similar conditions of the earth; commonly a minor division or part of a period.

A metrical unit of quantitative verse consisting of two or more cola.

The date at which a planet or comet has a longitude or position.

An analogous unit or division of classical Greek or Latin prose.

A period marked by distinctive character or reckoned from a fixed point or event

(Music) A group of two or more phrases within a composition, often made up of 8 or 16 measures and terminating with a cadence.

(astronomy) the precise date that is the point of reference for which information (as coordinates of a celestial body) is referred

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.

A unit of geological time

A group of digits separated by commas in a written number.

The number of digits that repeat in a repeating decimal. For example, 1/7 = 0.142857142857 ... has a six-digit period.

(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

Used to emphasize finality, as when expressing a decision or an opinion

A length of time.

A period of time in history seen as a single coherent entity; an epoch, era.

The punctuation mark “.” (indicating the ending of a sentence or marking an abbreviation).

(figurative) A decisive end to something; a stop.

The length of time during which the same characteristics of a periodic phenomenon recur, such as the repetition of a wave or the rotation of a planet.

(euphemism) Female menstruation; an episode of this.

A section of an artist's, writer's (etc.) career distinguished by a given quality, preoccupation etc.

Each of the divisions into which a school day is split, allocated to a given subject or activity.

Each of the intervals, typically three, of which a game is divided.

One or more additional intervals to decide a tied game, an overtime period.

The length of time for a disease to run its course.

An end or conclusion; the final point of a process etc.

(rhetoric) A complete sentence, especially one expressing a single thought or making a balanced, rhythmic whole.

(obsolete) A specific moment during a given process; a point, a stage.

(chemistry) A row in the periodic table of the elements.

(geology) A geochronologic unit of millions to tens of millions of years; a subdivision of an era, and subdivided into epochs.

(genetics) A Drosophila gene, the gene product of which is involved in regulation of the circadian rhythm.

(music) Two phrases (an antecedent and a consequent phrase).

(math) The length of an interval over which a periodic function, periodic sequence or repeating decimal repeats; often the least such length.

(archaic) End point, conclusion.

Designating anything from a given historical era. en

Evoking, or appropriate for, a particular historical period, especially through the use of elaborate costumes and scenery.

That's final; that's the end of the matter (analogous to a period ending a sentence); end of story.

To come to a period; to conclude.

To put an end to.

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.

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.

One of the great divisions of geological time; as, the Tertiary period; the Glacial period. See the Chart of Geology.

The termination or completion of a revolution, cycle, series of events, single event, or act; hence, a limit; a bound; an end; a conclusion.

A complete sentence, from one full stop to another; esp., a well-proportioned, harmonious sentence.

The punctuation point [.] that marks the end of a complete sentence, or of an abbreviated word.

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.

The time of the exacerbation and remission of a disease, or of the paroxysm and intermission.

A complete musical sentence.

To put an end to.

To come to a period; to conclude. [Obs.] "You may period upon this, that," etc.

An amount of time;

One of three periods of play in hockey games

A stage in the history of a culture having a definable place in space and time;

The interval taken to complete one cycle of a regularly repeating phenomenon

The monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause;

A punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations;

A unit of geological time during which a system of rocks formed;

The end or completion of something;