![half-decade half-decade](https://www.tekportal.net/wp-content/uploads/2019/02/half-decade-0703.jpg)
noun
- a period of ten years: the three decades from 1776 to 1806.
- a period of ten years beginning with a year whose last digit is zero: the decade of the 1980s.
- a group, set, or series of ten.
noun
- a period of ten consecutive years
- a group or series of ten
mid-15c., “ten parts” (of anything; originally in reference to the books of Livy), from Middle French décade (14c.), from Late Latin decadem (nominative decas), from Greek dekas (genitive dekados) “group of ten,” from deka “ten” (see ten). Meaning “period of ten years” is 1590s in English.