eighth

I. eighth¹ /eɪtθ/ BrE AmE adjective
coming 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).

Oxford Advanced Learner's Dictionary

eighth

eighth [eighth eighths] ordinal number, noun [eɪtθ] [eɪtθ]

ordinal number

8th There are examples of how to use ordinal numbers at the entry for fifth.

noun

each of eight equal parts of sth

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

eighth / eɪtθ / ordinal number

A2 8th written as a word:

He was/came eighth in the race.

Bob's birthday is on the eighth ( of June).

Collins COBUILD Advanced Learner’s English Dictionary

eighth

[e͟ɪtθ]
♦♦
eighths
1) ORD The eighth item in a series is the one that you count as number eight.
...the eighth prime minister of India.
2) FRACTION An eighth is one of eight equal parts of something.
The Kuban produces an eighth of Russia's grain, meat and milk.

Merriam-Webster's Advanced Learner's Dictionary

Merriam-Webster's Advanced Learner's Dictionary:

eighth

²eighth adj : occupying the number eight position in a series
• the eighth car in line
• the eighth edition
• Her son is in (the) eighth grade.
- eighth adv
• She finished eighth (in the race).