de·cade 
/ˈdɛˌkeɪd/ noun
plural de·cades /ˈdɛˌkeɪd/ noun [count] : a period of 10 years
▪ The war lasted nearly a decade. ▪ a decade of drought [=a drought that lasted 10 years] ▪ The bridge was built a decade ago. ; especially : a 10-year period beginning with a year ending in 0
▪ The decade of the 1920s runs from January 1, 1920 to December 31, 1929. ▪ the first decade of the 21st century ▪ There have been a lot of changes during/in/over the past two decades.
▪ The war lasted nearly a decade. ▪ a decade of drought [=a drought that lasted 10 years] ▪ The bridge was built a decade ago. ; especially : a 10-year period beginning with a year ending in 0
▪ The decade of the 1920s runs from January 1, 1920 to December 31, 1929. ▪ the first decade of the 21st century ▪ There have been a lot of changes during/in/over the past two decades.
