decadal

Adjective

 * 1) Of or related to the number ten.
 * 2) Of or related to a decade, in its various senses.
 * 3) *  2017, W. Hugh Woodin, In search of Ultimate-L: The 19th Midrasha Mathematicae Lectures (Version: January 30, 2017), p. 2
 * About the same time in a decadal sense, there was a rather unexpected discovery.

Usage notes
Although may be taken as any group of ten years, it is commonly restricted to the informal ten-year periods of the calendar whose last digits run from 0 to 9. In such contexts, decadal refers to such calendar periods while etc. refer to ten-year periods in other contexts.

Synonyms

 * See 

Etymology
From.

Adjective

 * 1)  ten days