Õ: ajaskaalal tähendab dekaad eesti keeles kümmepäevakut

olemus
aastakümme, kümneaastane ajavahemik

Wiktionary:
1. a period of ten years, particularly such a period beginning with a year ending in 0 and ending with a year ending in 9
The 1960s was a turbulent decade.

ISO 8601:
ajaskaalaühik väärtusega 10 aastat,
algab aastaga, mille number jagub kümnega;
väljaspool seda standardit tähendab ka
igasugust kümneaastast ajavahemikku
=
time scale unit of 10 calendar years, beginning with a year whose year number is divisible without remainder by ten
Note. Decade is also used to refer to an arbitrary duration of 10 years, however decade is not used as such in this document.

ülevaateid
https://en.wikipedia.org/wiki/Decade

vt ka
- dekaad (1)
- dekaad (2)