period

A period is a length of time.

Example: There was a short period when my computer stopped working.

A period is the dot that marks the end of most sentences in English. This ->. is a period.

Example: Should I use an exclamation mark or a period at the end of this sentence?

A woman's period is the time each month when she passes blood.

Example: I have missed two periods now. I think I must be pregnant.

And nothing else; and nothing less; used for emphasis.

Example: When I say "eat your dinner," it means "eat your dinner", period!