ninthPronunciation: /ˈnʌɪnθ/Translate ninth | into French | into German | into Italian | into Spanish Definition of ninth number 1constituting number nine in a sequence; 9th:the ninth century the ninth of March the ninth finisher or position in a race or competition:he came in ninth Music an interval spanning nine consecutive notes in a diatonic scale. Music the note which is higher by a ninth than the tonic of a diatonic scale or root of a chord. Music a chord in which the ninth note of the scale forms an important component. 2each of nine equal parts into which something is or may be divided. Derivatives ninthly adverb Spelling helpRemember that ninth begins with nin-.ninth in other Oxford dictionaries Definition of ninth in the US English dictionary