Learn how to say Eightieth correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word eightieth:
being the ordinal number of eighty in numbering or counting order, position, time, etc: often written 80th
(as noun) ⇒ the eightieth in succession
one of 80 approximately equal parts of something
(as modifier) ⇒ an eightieth part
the fraction equal to one divided by 80 (1⁄80)