e·lev·enth / iˈlevən[unvoicedth]/ • ordinal number constituting number eleven in a sequence; 11th: the eleventh century. ∎ (an eleventh/one eleventh) each of eleven equal parts into which something is or may be divided. ∎ the eleventh grade of a school. ∎ Mus. an interval or chord spanning an octave plus a fourth in the diatonic scale, or a note separated from another by this interval.PHRASES: the eleventh hour the latest possible moment: he refused to take a public stand until the eleventh hour of the campaign.