being from 90 to 99 years old
- some one whose age is in the 1990s
- one ninety years of age
- someone ninety yrs old.
Someone in his or her ninties, this is certainly, between 90 and 99 years. See also: Age by decade.
1776, coined in English with -an + Latin nonagenarius "containing ninety" (in belated Latin "some one ninety yrs old"), from nonagen "ninety each," regarding nonaginta "the amount ninety," from nonus "ninth" (see nones) + -genaria "ten times," from PIE *dkm-ta-, from *dekm- "ten" (see ten). As an adjective from 1893.
(letter.) Someone ninety yrs old.
So does a magnificent drawing of a head of a nonagenarian with a flowing beard who sat to him at Antwerp, together with a picture from the same head in the character of St Jerome; the drawing is now at Vienna, the picture at Lisbon.