This is the 2376th most frequent Dutch word.
twintigste
Twintigste: Twentieth.
The word 'twintigste' here is used as an ordinal numeral to indicate someone's position in a sequence.
De twintigste persoon in de rij ontving een speciale prijs.
The twentieth person in line received a special prize.
The word 'twintigste' functions to describe the numerical order of someone's birthday.
Op mijn twintigste verjaardag gaf ik een groot feest.
On my twentieth birthday, I threw a big party.
The word 'twintigste' in this case refers to the sequence of items (books) in a count for the specified period.