From Longman Dictionary of Contemporary Englisheightheighth1 /eɪtθ/ ●●● S3 W3 adjective HMNcoming after seven other things in a series in the eighth century her eighth birthday —eighth pronoun I’m planning to leave on the eighth (=the eighth day of the month).
Examples from the Corpus
eighth• This is the eighth day in a row that he has been late.the eighth• Classes start on the eighth.eightheighth2 noun [countable] one of eight equal parts of somethingExamples from the Corpus
eighth• Divide the pie into eighths. 