Select one word for the following group of words.

A period of ten years

Decade

The word that best describes a period of ten years is decade.

• Millennium is a period of one thousand years.
• Decade is a period of ten years.
• Century is a period of one hundred years.
• Fortnight is a period of two weeks, or fourteen days.

The word decade is the most appropriate because it specifically refers to a period of ten years. The other words do not have the same connotation of a specific number of years.