A length of time.

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

(now chiefly Canada, US, Philippines) 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.

(euphemistic) A noun "period" represents female menstruation, including the symptoms associated with it.

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.

(sports, chiefly ice hockey) Each of the intervals, typically three, of which a game is divided.

(sports, chiefly ice hockey) One or more additional intervals to decide a tied game, an overtime period.

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.

(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).

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

Designating anything from a given historical era. (Can we add an example for this sense?)

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

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