<p><strong>Noun:</strong></p><ul><li>A cardinal number, ten times nine.</li><li>A symbol for this number, as 90 or XC.</li><li>A set of this many persons or things.</li><li>Nineties, the numbers, years, degrees, or the like, from 90 through 99, as in referring to numbered streets, indicating the years of a lifetime or of a century, or degrees of temperature: His grandmother is in her nineties.</li></ul><p><strong>Adjective:</strong></p><ul><li>Amounting to 90 in number.</li></ul>