Of or related to ninetysomethings.

plural of nonagenarian

(astronomy) The middle to highest point of a part of an ecliptic that is above the horizon at any period of time.

Of or relating to the ninetieth degree or to a nonagesimal.

plural of nonagesimal

Alternative form of non-agenda

Not agentive.

plural of nonagenary

(rare) Of or related to the number ninety.

(astronomy, astrology, obsolete) Synonym of square or quadrature: a rising at a 90 degree angle to the position of another heavenly body, particularly the sun.