This is the 2167th most frequent Spanish word.
décimo
"Tenth" or "a tenth part; also a lottery ticket in Spain representing one-tenth of a full ticket."
Here, the word 'décimo' is used as an ordinal number to indicate the tenth in a sequence (Ana's birthdays).
Hoy celebramos el décimo cumpleaños de Ana.
Today we are celebrating Ana's tenth birthday.
In this context, 'décimo' refers to part of a lottery ticket, specifically one tenth of the ticket distributed in this system.
Compré un décimo de lotería para el sorteo de Navidad.
I bought a tenth lottery ticket for the Christmas draw.
The word 'décimo' is used as an ordinal number, indicating the floor's position in sequence within a building.