- A period of ten years. [from 17th c.]
- (physics, engineering) The interval between any two quantities having the ratio 10 to 1.
"There are decades between 1.8 and 18, between 25 and 250 and between 0.03 and 0.003."
- A series or group of ten things. [from 16th c.]
"a decade of soldiers"
- (Roman Catholicism) A series of ten Hail Marys in the rosary.
- (French historical) In the French Revolutionary calendar, a group of ten days. [from 18th c.]