Decade n. : A group or division of ten; esp., a period of ten years; a decennium; as, a decade of years or days; a decade of soldiers; the second decade of Livy.

Example:
What is the most interesting Decade of American history in the 20th century?

Taxonomy
Decade, free encyclopedia, Time measurement, last decade, decas, 12-hour clock, 24-hour clock, Atomic clock, chronology, late Latin, International standards, Cosmological decade, Absolute time and space, Astrarium, Astronomical year numbering, Barycentric, search, senses.

Defination from the web:
... Spacetime · Chronon · Cosmological decade · Planck epoch · Planck time · T-symmetry · Theory of relativity · Time dilation · Gravitational time ...