period

A length of time.

"There was a period of confusion following the announcement."

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

"Food rationing continued in the post-war period."

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

To come to a period; to conclude.

To put an end to.

Designating anything from a given historical era.

"a period TV commercial"

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

"I know you don't want to go to the dentist but your teeth need to be checked, period!"