From Longman Dictionary of Contemporary Englisheleventhe‧lev‧enth1 /ɪˈlevənθ/ ●●● S3 W3 adjective 1 coming after ten other things in a series in the eleventh century her eleventh birthday2 → the eleventh hour —eleventh pronoun I’m planning to leave on the eleventh (=the 11th day of the month).
Examples from the Corpus
eleventh• Tomorrow is her eleventh birthday.the eleventh• The meeting is on the eleventh.eleventheleventh2 noun [countable] one of eleven equal parts of something 