Period (noun)

1. A length or portion of time, typically one marked by certain characteristics or events.
2. A punctuation mark (.) used to indicate the end of a sentence or an abbreviation.
3. A menstrual cycle.
4. A stage in a series of events or a process.

Origin:

Late middle english: via old french from latin periodus "cycle, completion", from per- "through" + hodos "way". the sense "interval of time" dates from the early 17th century.

Examples:

1. The period of time from 1930 to 1950 was characterized by economic hardship.
2. The period is used to indicate the end of a sentence.
3. She has a regular 28-day menstrual period.
4. This period in his life was marked by great personal and professional success.
5. A long period of drought has left the region with a shortage of water.